Electrochemical Evaluation of Layered Perovskite YBa0.5Sr0.5Co1.5Fe0.5O5+δ Cathode as a Triple Ionic and Electronic Conductor for Protonic Ceramic Fuel Cells

Abstract

Protonic ceramic fuel cells (PCFCs) have receiving huge attention as a promising energy conversion device because of their high conversion efficiency, lack of fuel dilution, and high ionic conductivity at intermediate temperature regime (400 ∼ 600 oC). Although this fuel cell system can effectively solve the main obstacle for the commercialization of conventional solid oxide fuel cells, electrochemical performance is currently limited by the cathodic polarization due to insufficient catalytic activity. To overcome this issue, layered perovskite materials, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ, have been discovered as triple ionic and electronic conductor, which enables to simultaneously conduct H+/O2-/e-. Despite great advantages, there is large gap in the thermal expansion coefficient (TEC) between the cathode and electrolyte. Herein, we developed a new triple conducting cathode material, YBa0.5Sr0.5Co1.5Fe0.5O5+δ (YBSCF) to minimize TEC while maintaining the high electro-catalytic activity with excellent hydration properties. Structural analysis, hydration properties, and electrochemical performances of YBSCF cathode were investigated. In particular, the peak power density of YBSCF cathode based on BaZr0.4Ce0.4Y0.1Yb0.1O3-δ (BZCYYb4411) electrolyte attained 0.702 W cm-2 at 600 oC. Moreover, power output is fairly stable for 300 h without observable degradation by applying a constant voltage of 0.7 V at 600 oC.