Microstructure and performance of La0.58Sr0.4Co0.2Fe0.8O3−d cathodes deposited on BaCe0.2Zr0.7Y0.1O3−d by infiltration and spray pyrolysis

Abstract

La0.58Sr0.4Co0.2Fe0.8O3−d (LSCF) cathodes have been deposited on proton-conducting BaCe0.2Zr0.7Y0.1O3−d (BCZY27) electrolyte and studied in symmetric cells to investigate the cathode microstructure and electrochemical performance. Three different types of cathodes have been prepared: two prepared from a solution, infiltrated into a screen-printed BZCY27 porous backbone (4 and 12 infiltrations), and one prepared by spray pyrolysis onto a polished electrolyte. In all three cases, LSCF is obtained after annealing at 700 ◦C for 2 h. Analysis of the electrochemical impedance spectra between 450 ◦C and 600 ◦C in air, with varying p(H2O), reveals that the charge transfer contribution is the lowest for the backbone-infiltrated cathode while the oxygen dissociation/adsorption contribution is the lowest for the spray-pyrolyzed cathode. The area specific resistances increase with the water vapor pressure. The area specific resistances obtained are 0.61 ohm cm2 and 0.89 ohm cm2 at 600 ◦C for the spray-pyrolyzed LSCF cell in dry and humidified air, respectively; the corresponding resistances are 0.63 ohm cm2 and 0.98 oh cm2 for the 12 times infiltrated LSCF cell. These resistances are the lowest reported for LSCF cathodes on Ba(Ce,Zr)O3-based electrolytes and show the promise of low-temperature fabrication methods for these systems.