Infiltration of Lanthanum Doped Ceria into Nickel-Zirconia Anodes for Direct Butane Utilization in Solid Oxide Fuel Cells

Abstract

Ni-Gd doped ceria (Ni-GDC) anodes exhibit high durability during direct butane utilization in solid oxide fuel cells (SOFCs). However, the cells containing Ni-GDC anodes showed less performance compared to those containing conventional Ni-Y stabilized zirconia (Ni-YSZ) anodes, when zirconia-ceria solid solution formed at the interface between the YSZ electrolyte and Ni-GDC anode during co-sintering at high temperature in anode-supported SOFCs. The formation of the solid solution increases electrochemical impedance at low frequencies due to oxygen nonstoichiometric variation process. To prevent the formation of this solution, La doped ceria (LDC) was infiltrated into the Ni-YSZ anode after sintering. The maximum power density of the cell containing Ni-YSZ anode with LDC infiltration (Ni-YSZ+LDC) was higher than those containing Ni-YSZ and Ni-GDC anodes. Distribution of relaxation times (DRT) analysis revealed that the polarization resistance of fuel oxidation process decreased, and the oxygen nonstoichiometric variation process was not observed after LDC infiltration. Power was continuously generated over 100 h using butane fuel for the Ni-YSZ+LDC. No carbon deposition was observed after the durability test, because the LDC nanoparticles enhanced the catalytic activity toward carbon oxidation. The LDC infiltration is an method to obtain the comparability of performance and durability for direct butane utilization.