Anode-supported solid oxide fuel cells fabricated by single step reduced-temperature co-firing

Anode-supported solid oxide fuel cells (SOFCs) consisting of NiO-Y_0.16Zr_0.92O_2-δ (YSZ) anode support layer, NiO-YSZ anode functional layer, YSZ electrolyte and (La_0.8Sr_0.2)_0.98MnO_3-δ (LSM)-YSZ cathode were successfully fabricated by single-step cofiring at 1250°C. Cells were prepared by tape casting, with Fe₂O₃ sintering aid used to obtain a nearly dense YSZ electrolyte. Scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDS) showed no evidence of reactions or interdiffusion between layers during co-firing. The cells yielded area specific resistance of 0.44 Ωcm² and a maximum power density of 0.91 W/cm² at 800°C. Impedance spectroscopy measurements showed that the LSM-YSZ cathode polarization resistance was higher for the co-fired cathodes than for a cathode that was fired separately at an optimized temperature of 1175°C. However, reducing the cell co-firing time decreased cathode polarization resistance and increased cell power output. Analysis of SEM images showed that co-firing caused more sintering and coarsening than in the optimally-fired LSM-YSZ, reducing three-phase boundary density and explaining the increased cathode resistance.