Electrochemical Behaviour of Ni/YSZ Cermet Anodes Prepared by Combustion Synthesis

Homogeneous mixtures of nanocrystalline powders of NiO-YSZ were obtained by combustion synthesis, and used to prepare cermet/YSZ/cermet symmetrical cells by co-pressing, co-firing at 1450 °C, and reduction in 10 % H2 – 90 % N2 at 800 °C. The resulting Ni/YSZ cermets are porous and adherent to the electrolyte, and its metallic and ceramic components are uniformly distributed. Impedance spectroscopy was used to characterize these symmetrical cells in atmospheres containing H2 and H2O. These spectra show that the electrode reactions comprise of at least two processes at moderate and low relaxation frequencies respectively. The low frequency contribution is very dependent on the partial pressures of H2 and H2O. The polarization resistance obtained for these cermet electrodes is close to the order of magnitude of results reported for optimized Ni/YSZ and Ni/TZP cermet anodes prepared by different methods.