A novel composite cathode for low-temperature SOFCs based on oxide proton conductors

Abstract

A study has demonstrated that high power densities can be achieved in solid oxide fuel cells (SOFC) based on oxide proton conductors using properly designed proton-oxygen ion-electron conducting cathode derived from BZCY (barium-zirconium-cerium-yttrium) and SSC (Sm0.5Sr 0.5CoO3). This cathode material was found to be very active for oxygen reduction as it allows the simultaneous transport of proton, oxygen vacancy, and electronic defects, extending the active sites for oxygen reduction to a large extent and significantly reducing the cathodic polarization resistance. The composite fired at 1000°C offers unique transport properties and greatly increase the number of active sites, facilitating the electro-chemical reactions on the entire cathode surfaces. Additional improvement is also possible by optimization of cathode composition and microstructure, while reduction of the thickness of BZCY electrolyte could yield further increase in power density.