Effect of chromium poisoning on the electrochemical properties of NdBaCo2O5+δ cathode for IT-SOFCs

The effect of the Cr poisoning on the electrochemical properties of NdBaCo2O5+δ cathode for IT-SOFCs was investigated by the electrochemical impedance spectroscopy (EIS) and the cathodic polarization analysis. With the Cr poisoning, the area-specific resistances (ASRs) increased at 500–600 °C and did not increase with the increasing temperature. The Cr poisoning made a negative effect on the oxygen reduction reaction (ORR) below 600 °C. Besides, the Cr poisoning decreased the exchange current density i0. The activation energies of i0 were higher than those of the ASRs, indicating that the charge transfer process was the rate-determining step for the ORR. With or without the Cr poisoning, the polarization curves were independent of the on the sweep rate, indicating that there were no mass transport limitations on the ORR rate. Hence, the Cr poisoning deteriorated the charge transfer process of the ORR for NdBaCo2O5+δ and decreased the ORR activity.