Investigation of Fe-substituted in BaZr0.8Y0.2O3-δ proton conducting oxides as cathode materials for protonic ceramics fuel cells

Abstract

Cathode materials containing proton conductivity for protonic ceramics fuel cells (PCFCs) can increase the three phase boundary length of the air/cathode/electrolyte, and thus increase the reaction rate of proton with oxygen-species to form water in cathode side. In this work, a serious of Fe-substituted in BaZr0.8Y0.2O3-δ proton conducting oxides, abbreviated as BaZr0.8-xFexY0.2O3-δ (BZFY-2, BZFY-4, BZFY-6, BZFY-8), were synthesized and investigated as cathode materials for PCFCs, considering the phase structure, mean valence state and electrochemical performance. Accordingly, anode supported button cells using BaZr0.8-xFexY0.2O3-δ as cathodes are fabricated, and then performed from 700 to 550 °C. The cell performance with BZFY-6 presents optimal electrochemical performance with different Fe doping amount, and the peak power density of 322.23 mW cm−2 and the corresponding polarization resistance of 0.28 Ω cm2 are observed at 700 °C. Moreover, the corresponding electrode polarization processes are further studied by the distribution function of relaxation time (DRT) analysis, and three peaks of P1, P2 and P3 in DRT curves correspond the proton bulk diffusion, electrochemical reaction processes, and adsorption as well as diffusion process of oxygen, respectively. Preliminary results demonstrate that BZFY-6 can be a competitive promising for PCFCs.