Influence of Pr6O11 on oxygen electroreduction kinetics and electrochemical performance of Sr2Fe1.5Mo0.5O6-δ based cathode

Oxygen electroreduction kinetics and electrochemical performance of the Pr6O11-impregnated Sr2Fe1.5Mo0.5O6-δ – Ce0.8Sm0.2O1.9 (SFM–SDC) cathode have been first studied. By means of distribution of relaxation times and non-linear least squares analysis of impedance spectra were shown that the addition of Pr6O11 into the cathode leads to the increase in the rate of the low-frequency step. It is suggested that the observed phenomenon is associated with the increase in the rate of surface oxygen exchange. It is shown that the introduction of praseodymium oxide into the cathode results in a decrease in the area specific polarization resistances of the cathode at equilibrium potentials from 0.23 to 0.06 Ω cm2 at 800 °C in air. The maximum power density of symmetrical solid oxide fuel cell (SOFC) with impregnated SFM–SDC electrodes and supporting 760 μm La0.85Sr0.15Ga0.85Mg0.15O3-δ electrolyte without buffer/barrier and collector layers under air/wet hydrogen (dry CH4) condition was about 0.5 (0.26) W cm−2 at 800 °С. The overvoltage of the cathode was higher than that of the anode under air/wet hydrogen and vice versa when methane was supplied to the anode. The obtained results elucidate that the impregnated SFM–SDC is a promising cathode for SOFC application.