(Ni0.75Fe0.25–xMgO)/YSZ anode for direct methane solid-oxide fuel cells

(Ni0.75Fe0.25–xMgO)/YSZ samples—with a varying weight percentage x (0, 5%, 10%) of MgO with respect to Ni0.75Fe0.25—were prepared and studied as anodes for intermediate temperature solid oxide fuel cells (SOFCs) operated on humidified methane (3% H2O). Among the cells with different anode compositions, it was found that the cell with the (Ni0.75Fe0.25–5%MgO)/YSZ anode showed the highest power density, giving 648 mW cm−2 at 800 °C. The cells with MgO-doped anodes were able to operate stably for 20 h under a current density of 0.53 A cm−2 at 700 °C without observed degradation, while the cells without MgO degraded rapidly. The mechanisms responsible for the superior performance and duration of the (Ni0.75Fe0.25–5%MgO)/YSZ anode were analyzed.

► Novel SOFC anode material (Ni0.75Fe0.25–xMgO)/YSZ is investigated in methane fuel. ► Electrochemical performance of the novel anode is much better than Ni/YSZ anode. ► SOFC with the MgO-doped novel anode can operate stably on methane fuel. ► Failure of traditional anode in hydrocarbon fuel is caused by carbon fiber growth. ► MgO in Ni-based anode can suppress carbon fiber growth or strengthen the anode.