Sm0.2(Ce1−xTix)0.8O1.9 modified Ni–yttria-stabilized zirconia anode for direct methane fuel cell

Sm0.2(Ce1−xTix)0.8O1.9 (SCTx, x = 0–0.29) modified Ni–yttria-stabilized zirconia (YSZ) has been fabricated and evaluated as anode in solid oxide fuel cells for direct utilization of methane fuel. It has been found that both the amount of Ti-doping and the SCTx loading level in the anode have substantial effect on the electrochemical activity for methane oxidation. Optimal anode performance for methane oxidation has been obtained for Sm0.2(Ce0.83Ti0.17)0.8O1.9 (SCT0.17) modified Ni–YSZ anode with SCT0.17 loading of about 241 mg cm−2 resulted from four repeated impregnation cycles. When operating on humidified methane as fuel and ambient air as oxidant at 700 °C, single cells with the configuration of SCT0.17 modified Ni–YSZ anode, YSZ electrolyte and La0.6Sr0.4Co0.2Fe0.8O3–Sm0.2Ce0.8O1.9 (LSCF–SDC) composite cathode show the polarization cell resistance of 0.63 Ω cm2 under open circuit conditions and produce a peak power density of 383 mW cm−2. It has been revealed that the coated Ti-doped SDC on Ni–YSZ anode not only effectively prevents the methane fuel from directly impacting on the Ni particles, but also enhances the kinetics of methane oxidation due to an improved oxygen storage capacity (OSC) and redox equilibrium of the anode surface, resulting in significant enhancement of the SCTx modified Ni–YSZ anode for direct methane oxidation.

Research highlights
► Ni–YSZ anode modified with Ti-doped SDC is used for direct utilization of methane fuel.
► Both the Ti-doping content and loading level affect the resulted anodes performance.
► The coated layers increase the oxygen storage capacity and redox behavior of the anodes.