Development of LaCaNiCuO Materials for Oxygen Permeation Membranes and Cathodes for Intermediate-Temperature Solid Oxide Fuel Cells.

The LaCaNiCuO (y = 0.0-0.4) nickelates, synthesized via a solid-state reaction method, are investigated as prospective materials for oxygen permeation membranes and IT-SOFC cathodes. The obtained oxides are single-phase and possess a tetragonal structure (/ sp. gr.). The unit cell parameter and the cell volume increase with Cu-substitution. The interstitial oxygen content and total conductivity decrease with Cu-substitution. The low concentration of mobile interstitial oxygen ions results in a limited oxygen permeability of Cu-substituted LaCaNiO ceramic membranes. However, increasing the Cu content over y = 0.2 induces two beneficial effects: enhancement of the electrochemical activity of the LaCaNiCuO (y = 0.0; 0.2; 0.4) electrodes and decreasing the sintering temperature from 1200 °C to 900 °C. Enhanced electrode activity is due to better sintering properties of the developed materials ensuring excellent adhesion and facilitating the charge transfer at the electrode/electrolyte interface and, probably, faster oxygen exchange in Cu-rich materials. The polarization resistance of the LaCaNiCuO electrode on the CeSmO electrolyte is as low as 0.15 Ω cm and 1.95 Ω cm at 850 °C and 700 °C in air, respectively. The results of the present work demonstrate that the developed LaCaNiCuO-based electrode can be considered as a potential cathode for intermediate-temperature solid oxide fuel cells.