Preparation and Properties of Fe-Based Double Perovskite Oxide as Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cell

Abstract

The existence of various valence states of B-site ions modifies the material’s catalytic activity, indicating the possibility of partial substitution of Fe by higher valence ions. LaBaFe2-xMoxO5+δ (x=0, 0.03, 0.05, 0.07, 0.1, LBFMx), as intermediate-temperature solid oxide fuel cell (IT-SOFC) cathode materials, were prepared and evaluated, and the influence of Mo replacement on the crystal structure, physical and chemical properties, and electrochemical properties was investigated. At a doping concentration above 0.1, the Mo substitution enhanced cell volume, and the lattice expansion caused the formation of the impurity phase BaMoO4. At the temperature range of 30–750 °C, the thermal expansion coefficient of LBFMx decreased from 13.2×10-6·K-1 to 9.09×10-6·K-1. The partial substitution of Fe in the B-site by Mo enhanced the adsorbed oxygen content and oxygen vacancy concentration, thus increasing the oxygen reduction reaction performance. The electrochemical performance of LBFM0.1 was enhanced, and the symmetric cell LBFM0.1|CGO|LBFM0.1 had the lowest polarization resistance (Rp) of only 0.017 Ω·cm2 at 800 °C. The anode-supported single cell LBFM0.1|CGO|NiO+CGO had a peak power density of 599 mW·cm-2. The good electrochemical behavior of LaBaFe1.9Mo0.1O5+δ indicates that it is a potential IT-SOFC cathode material.

Keywords: IT-SOFC, Fe-based, Mo doping, electrochemical performance