Improved coking resistance of direct ethanol solid oxide fuel cells with a Ni-Sx anode

In this study, the coking resistance of anode supported direct ethanol solid oxide fuel cell with a Ni-Sx anode was investigated comparatively with the conventional cell using pure Ni catalyst. The surface catalytic properties of Ni were manipulated via depositing a layer of S atoms. It was confirmed that on the surface of Ni, a combination of S monolayer and elemental S was formed without producing Ni3S2 phase. The developed Ni-Sx cell exhibited a significantly improved coke resistivity in ethanol feed while maintaining an adequately high performance. The S species on Ni enabled the suppression of the coke formation as well as the alleviation of the metal dusting effect of the anode structure. After operating in ethanol fuel for identical period of time at 850 °C, a maximum power density of 400 mW cm−2 was sustained whereas the conventional cell performance decreased to less than 40 mW cm−2 from the original 704 mW cm−2. In an optimized stability test, the Ni-Sx cell operated at 750 °C for more than 22 h until the fuel drained without any degradation.