Enhancing the oxygen reduction reaction activity and durability of a solid oxide fuel cell cathode by surface modification of a hybrid coating

Abstract

While (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) has been one of the most investigated materials for a long time, its relatively insufficient oxygen reduction reaction (ORR) activity and inherent performance degradation are still two main obstacles to its massive application on oxygen-ion conducting solid oxide fuel cell (SOFC). To solve those issues, a composite of Pr6O11 and NiO has been deposited on LSCF successfully via a facile infiltration method in this study. The modified LSCF cathode exhibits ∼30% lower polarization resistance than LSCF. The excellent performance promotion may be due to the synergistic effect of Pr6O11 and NiO on the LSCF surface. The distribution of relaxation time (DRT) analyses of electrochemical impedance spectra (EIS) in different oxygen partial pressure and long-term operation indicate that the performance enhancement is caused by the facilitated oxygen surface adsorption-dissociation process and suppression of Sr segregation on modified LSCF cathode, thus achieving a higher peak power density of 1.40 W cm−2 at 800 °C and better long-term operation stability of only 3% voltage decline rate after 80 h operation. These results indicate that Pr6O11 and NiO composite modification is a promising method for improving the electrochemical performance of LSCF.