A Short Review on the Proton Conducting Electrolytes for Solid Oxide Fuel Cell Applications

Abstract

The performance of solid oxide fuel cells (SOFCs) mostly relies on the electrolyte component, which is considered the heart of the SOFC. Since intermediate-temperature SOFCs (IT-SOFCs) have become popular, more consideration has been given to the performance of the electrolyte components for proton-conducting SOFCs (H-SOFCs). Potential electrolytes for H-SOFCs must meet the three basic requirements of good sinterability, high chemical stability and high ionic conductivity. Unfortunately, studies have shown that it is very difficult to find a material that meets all three requirements simultaneously. BaZrO3 and BaCeO3 are two common proton conducting electrolytes used in H-SOFCs. BaZrO3-based proton conductors showed perfect chemical stability in CO2 and H2O atmospheres but have poor sinterability, while BaCeO3-based proton conductors showed high proton conductivity and good sintering behaviour but could easily react with CO2 and H2O atmospheres. In contrast, SrCeO3 has low conductivity due to its lower rate of proton transport. Few literature reports describe efforts to improve the sintering behaviour and conductivity of electrolytes. Thus, this review highlights developing trends in electrolyte sintering behaviour and conductivity, which will support efforts to develop high-performance proton-conducting SOFCs.