Topological Ion Optimized Composite Cathode for Proton-Conducting Solid Oxide Fuel Cells

Abstract

Proton ceramic fuel cells (PCFCs) are favored for their excellent performance under medium-temperature conditions. However, their advancement is limited by sluggish oxygen kinetics and the lack of highly compatible cathodes. Nanocatalysts produced via in situ exsolution have emerged as a promising solution to overcome the limitations of conventional PCFC cathode catalysts. A novel three-phase composite cathode, synthesized via in situ ion topology engineering, achieves enhanced performance in PCFCs. By introducing the transition metal V into BaCe0.25Fe0.75O3-δ (BCF), BaFe2O4 nanoparticles are formed on the cathode surface through Fe-Ba-V ion exchange, simultaneously creating a BaCeO3-BaFe1-xVxO3 co-catalyzed interface. This composite cathode exhibits superior oxygen adsorption-dissociation capabilities and serves as an efficient proton conduction carrier. The self-assembled BaFe2O4, with its low thermal expansion coefficient, reduces the material's overall thermal expansion and improves cathode-electrolyte compatibility. Additionally, the cathode's stability and catalytic activity are significantly enhanced. PCFCs utilizing BCF-V as the cathode achieved an impressive power density of 1.73 W cm−2 at 650 °C and maintained stable operation for over 200 h at 600 °C.