Development of conducting composite cathodes for IT-SOFCs

Decreasing the working temperature of solid oxide fuel cells (SOFCs) to 400 °C–600 °C is a primary concern for current fuel cell research. Unfortunately decrease in operating temperatures leads to increase in cathode polarization, which deteriorates electrochemical activity of the cathode for oxygen reduction reaction (ORR). Consequently, the search of new cathode materials is one of the critical bottle-neck towards the development of intermediate-temperature SOFCs (IT-SOFCs). In this study, we have successfully synthesized Bi0.5Sr0.5FeO3-δ and Bi0.5Sr0.5FeO3-δ-Gd0.1Ce0.9O2-δ((1-x) BSFO-xGDC) composite cathodes with varying compositions (x = 50, 40, 30, and 20wt%). The crystal structure, microstructure, electrochemical properties and performance stability of these composite cathodes have been comprehensively evaluated using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Our results demonstrate that the introduction of Gd0.1Ce0.9O2-δ( GDC) has a significant impact on the electrochemical performance of the composite cathodes. Among the different compositions studied, the cathode with a composition of x = 70 wt% exhibits particularly promising electrochemical properties. The electrode resistance polarization of 70BiSFO-30GDC is 0.39 Ωcm2 and 0.8 Ωcm2 for symmetrical and half-cell at 600 °C. The preliminary results of this study reveal that the 70BiSFO-30GDC composite cathode demonstrates remarkable ORR activity. Further investigations and comprehensive analyses are warranted to validate and explore the full potential of the 70BiSFO-30GDC composite cathode in the context of SOFC applications.