Solid State Ionics, Vol.332, 70-76, 2019
Evaluation of electrochemical properties of LaNi0.6Fe0.4O3-delta - Ce0.9Gd0.1O1.95 composite as air electrode for SOFC
The electrochemical properties of the composite electrodes of LaNi0.6Fe0.4O3-delta-Ce0.9Gd0.1O1.95 in various compositions were measured by electrochemical impedance spectroscopy as a function of temperature and p (O-2). The enhancement of area-specific conductivity, sigma(E), was found higher than that of the single-phase porous LaNi0.6Fe0.4O3-delta electrode. sigma(E) greatly depends on their volume ratio, where sigma(E) increases with the increase of the volume fraction of Ce0.9Gd0.1O1.95 phase up to 50%. Above 50% of the volume ratio, sigma(E) decreases which could be due to the loss of its surface area density and connectivity between LaNi0.6Fe0.4O3-delta particles. The enhancement degree of sigma(E) was evaluated using the transmission line model for the porous-mixed ionic and electronic electrodes. The calculated model is close to the measured sigma(E), showing that the enhancement of sigma(E) is not only because of the enhancement of ionic conducting pathways but also possibly due to the decrease of the surface reaction resistivity upon contact with the Ce0.9Gd0.1O1.95.