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% I max ) 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.

Voltammetry, impedance spectroscopy, and operando vibrational Raman spectroscopy were used to examine the resilience of traditional and modified Ni-based SOFC anodes to environmental reduction/oxidation (redox) cycling. Traditional anodes were fabricated from Ni yttrium stabilized zirconia (YSZ) cermets while modified anodes consisted of the Ni-YSZ cermet containing 4 wt % Al 2 TiO 5 (ALT). Anodes were part of full membrane electrode assemblies that included a YSZ electrolyte support and a LSM cathode. Experiments were performed at 800 °C. To examine anode resilience to redox cycling, cells operated with hydrogen under galvanostatic conditions for 20 min prior to oxidation at OCV using either H 2 O or O 2 . While H 2 O only partially oxidized anodes, O 2 exposure fully oxidized anodes and rapidly accelerated degradation in undoped cells. Undoped cells typically suffered a 50% loss in conversion efficiency after approximately 15−20 redox cycles with O 2 . Under equivalent conditions, cells with ALT doped anodes degraded on average only 13 ± 3%. EIS modeling and ex situ FE-SEM measurements provide further insight into the mechanisms responsible for enhanced resilience shown by Ni-YSZ cermet anodes doped with ALT.

Spectroscopic and electrochemical techniques were used to examine the benefits of adding small amounts of aluminum titanate (Al2TiO5 or ALT) to standard NiO–yttria-stabilized zirconia (YSZ)-based solid oxide fuel cell anodes operating with methane at 800 °C. Combining small amounts (4% by mass) of ALT with NiO–YSZ leads to the formation of secondary phases that improve anode carbon tolerance via multiple reaction mechanisms. Raman data show that carbon forms on both ALT-doped and undoped anodes at open-circuit voltage and with applied bias as evidenced by the vibrational band of highly ordered graphite at 1560 cm–1. However, ALT-doped anodes limited the amount of carbon that forms on both the surface and within the bulk, resulting in improved performance for up to 12 h of exposure to CH4. Results show that ALT-enhanced anodes accumulate ∼25% less carbon on the surface under open-circuit conditions and that increasing polarizations to 50% of the maximum current and beyond results in no observable carbon accumulation. These observations are used to deduce possible mechanisms that describe how secondary phases suppress carbon accumulation.

No abstract