Enhanced reaction kinetics of BCFZY-GDC-PrOx composite cathode for low-temperature solid oxide fuel cells

Abstract

Solid oxide fuel cells function as promising power generation devices in the 21 century, but the lack of effective active cathodes at a low-temperature hinders their practical applications. In this study, BaCo0.4Fe0.4Zr0.1Y0.1O3-σ-Ce0.8Gd0.2O1.9 (BCFZY-GDC) composite cathode with infiltration of PrOx nanoparticles is systematically investigated. It is found that not only the composite cathodes demonstrate excellent phase compatibility, but also their reaction kinetics toward oxygen reduction reactions is substantially improved. Simultaneously, when the amount of the PrOx nanoparticles is about 18 mg/cm2, the Rp value of the resultant cathode reaches the minimum, and the value is about 0.082 Ω·cm2 at the operating temperature of 600 °C, which is only 25.3% of that of the cathode without PrOx. Furthermore, at operating temperatures of 700 °C, 650 °C, and 600 °C, the single-cell's power densities with the configuration of Ni-YSZ/YSZ/GDC/Pr18 (PrOx in BCFZY-GDC cathode is 18 mg/cm2) can reach about 1.55, 1.02, 0.56 W cm−2 under H2 atmosphere, and 1.22, 0.78, 0.39 W cm−2 under 20%CH3OH-80%N2 atmosphere, respectively, which is among the top high values based on the commercially available Ni-YSZ anode-supported single cells. The mechanism investigation further verifies that the enhanced reaction kinetics can be attributed to the improved surface exchange and ion transfer at the cathode's oxygen reduction reactions.