Low Nickel, Ceria Zirconia-Based Micro-Tubular Solid Oxide Fuel Cell: A Study of Composition and Oxidation Using Hydrogen and Methane Fuel

The study examines the effect of using low nickel (Ni) with high ceria (CeO 2 ) anode content towards the oxidation of H 2 and CH 4 fuel by evaluating the activation energy of the ohmic process and charge transfer process. Using a micro-tubular solid oxide fuel cell (MT-SOFC), the anodes are made up of 50% YSZ with varying NiO:CeO 2 percentages from 0% NiO, 50% CeO 2 to 50% NiO, 0% CeO 2 . The performance is measured based on maximum power density (MPD), electrochemical impedance spectroscopy (EIS) and activation energy, E a of the ohmic (Rohm) and charge transfer (R ct ) processes. We found that by lowering the Ni content to lower than 50% NiO, anode conductivity will drop by 7-fold. An anode containing 37.5% NiO, 12.5% CeO 2 yield MPD of 41.1 and 2.9 mW cm −2 when tested on H 2 and CH 4 fuels thus have the lowest Ni content without an abrupt negative effect on the MPD and EIS. The significant effect of conductivity drops on MPD and EIS are observed to occur at 25% NiO, 25% CeO 2 and lower NiO content. However, anode content of 25% NiO, 25% CeO 2 has the lowest E a for R ct (29.74 kJ mol −1 ) for operation in CH 4 , making it the best anode composition to oxidize CH 4 . As a conclusion, an anode containing 25% NiO:25% CeO 2 :50% YSZ and 37.5% NiO:12.5% CeO 2 :50% YSZ shows promising results in becoming the low Ni anode for coking-tolerant SOFC.