Low temperature preparation and performance of Ni/YSZ anode with a multi-layered structure for SOFC

Ni/yttria-stabilized zirconia (YSZ) anodes with a multi-layered structure are prepared on YSZ substrates by a low temperature process using electron-beam evaporation method. The Ni/YSZ anode is obtained by reducing a NiO/YSZ anode, and both Ni and YSZ layers have no impurity phases. Scanning ion microscopy (SIM) observation of the cross-section of the anode shows a well-separated structure without Ni diffusion and agglomeration. Tight adhesion between the Ni and YSZ layers is realized by the low temperature process at 800 °C. The current–voltage and current–power characteristics for three separate single cell samples with the multi-layered anode are measured. The maximum power densities of the single cells using an YSZ as an electrolyte (0.5 mm thick) with a four-layered anode, a six-layered anode, and a 10-layered anode are obtained to be 0.14, 0.12, and 0.32 W/cm2 at 800 °C, respectively. The improvement in the performance of the 10-layered anode compared with the four-layered and six-layered anodes is mainly due to an increase in the length of triple phase boundary in the structure and enhancement in the diffusivity of fuel gas.