Nickel–Ceramic Electrodes with High Nickel Content for Solid Electrolyte Electrochemical Devices

Composite powders (66 wt % NiO + 34 wt % Zr0.84Y0.16O1.92 were obtained according to the solution combustion synthesis technique by crystallization of nickel oxide particles on the surface of Zr0.84Y0.16O1.92particles. The samples pressed from powders after sintering and reduction in moist hydrogen had high electrical conductivity, more than 16 × 103 S cm–1 at room temperature. Impedance spectroscopic studies have shown that in a humid atmosphere of Ni – Zr0.84Y0.16O1.92, electrodes formed on the surface of a dense Zr0.84Y0.16O1.92 electrolyte have low electrochemical activity. The impregnation of the electrodes with a solution of cerium nitrate followed by thermolysis made it possible to increase the electrochemical activity of the electrode by two to three orders of magnitude. An analysis of the electrochemical impedance spectra through the calculation of the distribution function of the relaxation time showed that the rate of hydrogen oxidation at the electrodes is limited by surface–adsorption processes. After impregnation, the gas diffusion resistance significantly limits the electrode reaction rate.