A comparative study of fabrication and performance of Ni/3 mol % Y2O3-ZrO2 and Ni/8 mol% Y2O3-ZrO2 cermet electrodes

A comparative study was carried out on the fabrication and performance of Ni/3 mol % Y2O3-ZrO2 (Ni/TZ3Y) and Ni/8 mol % Y2O3-ZrO2 (Ni/TZ8Y) cermet anodes. The electrochemical performance of Ni/TZ3Y and Ni/TZ8Y cermet anodes was investigated in relation to the fabrication processes such as the coarsening treatment of zirconia and Ni/zirconia cermet powder and the sintering temperature of the anode. For Ni/TZ3Y cermet electrodes, the effect of the coarsening treatment of TZ3Y and Ni/TZ3Y cermet powders on the polarization performance of the anode was very small. On the other hand, coarsening of TZ8Y and Ni/TZ8Y cermet powders had a profound effect on the performance of Ni/TZ8Y cermet anodes. The best performance was found to be the Ni/TZ8Y cermet anodes prepared from Ni/TZ8Y cermet powder previously coarsened at 1300degreesC. Sintering Ni/zirconia cermet anodes at high temperatures (e.g., 1400degreesC) was essential to reduce both the electrode ohmic resistance and electrode polarization resistance. The results demonstrated that the sintering behavior of the zirconia phase in the cermets affect not only the formation of zirconia-to-zirconia ionic network but also the formation of the Ni-to-Ni electrical network of the Ni/zirconia cermet anodes and thus the electrical contact between the Ni phase in the cermet and YSZ electrolyte. (C) 2003 The Electrochemical Society.