Effects of oxygen reduction and hydration on performance of protonic ceramic fuel cells in hydrocarbon fuels

Abstract

The performance of composite cathodes with different cathode materials, such as (Ba0.95La0.05) (Fe0.8Zn0.2)O3-δ (BLFZ), (Ba0.5Sr0.5) (Co0.8Fe0.2)O3-δ (BSCF), and (La0.8Sr0.2)CoO3-δ (LSC), are investigated to find the effects of the oxygen reduction reaction (ORR) and hydration on the fuel cell performance of protonic ceramic fuel cells. BLFZ, which exhibits the highest degree of hydration among these three materials, demonstrates the best electrode performance in hydrogen fuel, although BLFZ shows poor ORR activity compared with BSCF and LSC. When LSC is added into the BLFZ composite cathode to enhance the ORR activity, the electrode performance in H2 fuel improves slightly, but that in CH4 fuel improves significantly, thereby resulting in an increase in the power density from 0.48 to 0.72 W/cm2 in CH4 fuel at 600 °C. By analyzing the relaxation time distribution, the contributions of the ORR and hydration reaction at the cathode to the performance of H2 and CH4 fuels are investigated separately. It is demonstrated that the ORR activity and hydration reaction can be optimized simultaneously by infiltrating the ORR catalysts into cathode materials with high hydration.