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 800degreesC. 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 rum 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/cm(2) at 800degreesC, 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. (C) 2004 Elsevier B.V. All rights reserved.