The evaluation of triple conductor Ba0.95La0.05Fe0.8Zn0.2O3-δ as air electrode for reversible protonic ceramic fuel cell

Abstract

High-efficiency and low-pollution energy conversion devices as protonic ceramic fuel cells have attracted the interest of a wide range of researchers, and the air electrode materials play vital roles in the operation of fuel cell and also dominate the electrolysis of steam to hydrogen process. Here we report the triple conductor Ba_0.95La_0.05Fe_0.8Zn_0.2O_3−δ (BLFZ) with high proton concentration as air electrode to evaluate its electrochemical performance. The BLFZ powder could remain its cubic structure with the lattice parameter of 4.063 Å in humid air at 700 °C. The electrical conductivity relaxation measurement proves that the proton uptake in BLFZ could be taken in hydrogenation method, but shows slower proton uptake kinetics than oxygen ion. And in symmetrical cell test, the BLFZ electrode exhibits obvious competition in oxygen and water molecular adsorption, where the addition of steam in air could result in higher polarization resistance and shows better electrochemical performance in humid pure O₂ atmosphere. When apply the BLFZ as air electrode in fuel cell, it shows 0.623 Wcm⁻² power density at 700 °C, and in electrolysis mode, the BLFZ air electrode shows good catalytic activity for water electrolysis with 0.5 Acm⁻² current density at 1.3 V under 600 °C.