Enabling fast ionic transport in CeO2–La1−2xBaxBixFeO3 nanocomposite electrolyte for low temperature solid oxide fuel cell application

Abstract

Recent studies indicate that electrolyte ionic conductivity plays a pivotal role in reducing the operating temperature of solid oxide fuel cells (SOFCs). In this regard, nanocomposite electrolytes have drawn significant attention owing to their enhanced ionic conductivity and fast ionic transport. In this study, we fabricated CeO₂–La_1−2xBa_xBi_xFeO₃ nanocomposites and tested them as a high-performance electrolyte for low-temperature solid oxide fuel cells (LT-SOFCs). The prepared samples were characterized by their phase structure, surface, and interface property via transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), followed by being applied in SOFCs to examine their electrochemical performance. In the fuel cells, it was found that the optimal composition 90CeO₂–10La_1−2xBa_xBi_xFeO₃ electrolyte-based SOFC delivered a peak power density of 834 mW cm⁻² along with an open circuit voltage (OCV) of 1.04 V at 550 °C. A comparative study revealed that the nanocomposite electrolyte exhibited a total conductivity of 0.11 S cm⁻¹ at 550 °C. Moreover, the rectification curve manifested the formation of the Schottky junction, suppressing the electronic conduction. This study conclusively shows that the addition of La_1−2xBa_xBi_xFeO₃ (LBBF) into ceria electrolyte is a viable approach for constructing high-performance electrolytes for LT-SOFCs.