Fabrication and characterization of planar-type SOFC unit cells using the tape-casting/lamination/co-firing method

In this study, solid oxide fuel cells (SOFCs) consisting of a NiO-YSZ anode, a NiO/YSZ-YSZ functional layer, YSZ electrolyte and a (La_0.8Sr_0.2)MnO₃ + yttria-stabilized zirconia (LSM-YSZ) cathode were fabricated by tape-casting, lamination, and a co-firing process. NiO/YSZ-YSZ nano-composite powder was synthesized for the anode functional layer via the Pechini process in order to improve cell performance. After optimization of the slurries for the anode functional anode, electrolyte and cathode, all components were casted so as to fabricate the monolithic laminate. The co-firing temperature was optimized to minimize second phase formation between the (La_0.8Sr_0.2)MnO₃ (LSM) and yttria-stabilized zirconia (YSZ) and to increase the sinterability of the YSZ electrolyte. The YSZ electrolyte was fully sintered with the addition of 0.5 wt% CuO, and the second phases of La₂Zr₂O₇ and SrZrO₃ did not form at 1350 °C. Ni-YSZ anode-supported unit cells were fabricated by co-firing at 1250-1400 °C. The unit cells co-fired at 1250 °C, 1300 °C, 1325 °C, 1350 °C and 1400 °C had maximum power densities of 0.18, 0.18, 0.30, 0.46 and 0.036 W/cm², respectively, in humidified hydrogen (∼3% H₂O) and air at 800 °C.