Feasibility of Ni-based cermet anode for direct HC SOFCs: Fueling ethane at a low S/C condition to Ni-ScSZ anode-supported cell

The feasibility of a Ni-based cermet anode for direct hydrocarbon (HC) SOFCs was investigated with ethane fuel as a step towards utilizing higher HCs such as propane and butane. The possibility of stable operation of SOFCs with ethane fuel at a low steam/carbon (S/C) ratio of 1.2 mol% H₂O-98.8 mol% C₂H₆ was investigated with anode-supported SOFCs utilizing a scandia stabilized zirconia (ScSZ) electrolyte and a Ni-ScSZ anode. Severe carbon deposition was observed around the anode especially at the fuel injection port during the cell tests at T = 973 K. The amount of deposited carbon became smaller with decreasing operation temperature, and a stable cell operation was achieved at T ≈ 823 K without severe carbon deposition over a week. However, at a low fuel utilization rate (U_f) around 20%, nickel was heavily disintegrated accompanied by severe carbon deposition even at T ≈ 823 K. With increasing U_f, the disintegration became less, and a stable cell operations were achieved only with a small amount of deposited carbon for over a week at high U_f > 46%.