Patterned Nickel Anode Stability in SOFC Environments with H2, CO and CH4 Fuel Feeds
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Single cell solid oxide fuel cells supported on single crystal YSZ electrolytes with patterned Ni anodes fabricated through sputter deposition and photolithographic techniques and with porous LSM/YSZ cermet cathodes were tested electrochemically to assess the stability of the Ni anodes in SOFC environments. Anode stability and electrochemical performance for H2, CO and CH4 electrochemical oxidation were characterized at cell temperatures between 750 ºC and 800 ºC under humidified (PH20/Pfuel = 0.05) conditions. Changes in performance of anodes polarized by typical working fuel cell overpotentials (100 - 200 mV) were compared to anodes kept at open circuit conditions. An increase in surface roughness was much greater for the polarized anodes than those kept under open circuit conditions. Electrochemical impedance spectroscopy and sweep voltammetry, over 10 continuous hours of testing, consistently showed constant performance for the polarized anodes and a drop in performance for the open circuit anodes.