Microstructure and performance of La_0.58Sr_0.4Co_0.2Fe_0.8O_3−δ cathodes deposited on BaCe_0.2Zr_0.7Y_0.1O_3−δ by infiltration and spray pyrolysis

La0.58Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathodes have been deposited on proton-conducting BaCe0.2Zr0.7Y0.1O3−δ (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 2h. 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 0.61Ωcm2 and 0.89Ωcm2 at 600°C for the spray-pyrolyzed LSCF cell in dry and humidified air, respectively; the corresponding resistances are 0.63Ωcm2 and 0.98Ωcm2 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.