Improved electrochemical performance of Ca2Fe1.4Co0.6O5–Ce0.9Gd0.1O1.95 composite cathodes for intermediate-temperature solid oxide fuel cells

Abstract

The performance of Ca2Fe1.4Co0.6O5–Ce0.9Gd0.1O1.95 (CFC–CGO) composite cathode has been investigated for potential application in intermediate-temperature solid oxide fuel cells (IT-SOFCs). The composite cathodes are prepared and characterized by XRD and SEM, respectively. The electrochemical properties of the composite cathodes are investigated using AC impedance and DC polarization methods from 500 to 700 °C under different oxygen partial pressures. The polarization resistance (Rp) decreases with the increase of CGO content in the composite electrode. The addition of 40 wt.% CGO in CFC results in the lowest Rp of 0.48 Ω cm2 at 700 °C in air. Oxygen partial pressure dependence study indicates that the charge-transfer process is the rate limiting step for oxygen reduction reaction. CFC-40CGO composite cathode exhibits the lowest overpotential of about 67 mV at a current density of 85 mA cm−2 at 700 °C in air.