Enhanced power density of metal-supported solid oxide fuel cell with a two-step firing process

In order to solve the Ni-coarsening problem during fabrication, Ni-supported solid oxide fuel cells (SOFCs) were fabricated using a two step process; co-sintering the cell at a high temperature in air and reducing it at a low temperature. NiO, NiO–YSZ, and YSZ (yttria-stabilized zirconia) were tape casted and the laminated cell was co-fired at 1300 °C in air to form a three-layered half cell and then reduced at 800 °C in H2 in order to convert the NiO to the Ni support. Thin and strong Ni-supported SOFC was successfully fabricated by the two-step process without visible cracks. The anodic microstructure was compared with that sintered at 1350 °C in H2. The particle size of Ni in anode, reduced at 800 °C, was much smaller (< 1 μm) and more uniform than that of Ni sintered at 1350 °C in H2 (∼ 5 μm). The cell with the two-step fired anode showed a power density as high as ∼ 0.93 W/cm2 when it was measured at 800 °C using LSCF as cathodes. This was about twice higher than that of the cell co-fired at 1350 °C in H2 and thus the highest value among many metal-supported cells based on a YSZ electrolyte. Thus, the anode microstructure is critical in the performance of metal-supported SOFC.