Preparation and Properties of Bi_1–xCa_xFeO_3–δ Cathode Materials for Intermediate-Temperature Solid Oxide Fuel Cell

Developing cathode materials with superior electrochemical activity is of great importance to the application of intermediate-temperature solid oxide fuel cell (IT-SOFC). In this paper, Bi_1–xCa_xFeO_3–δ (BCFx, x=0.1, 0.2 and 0.3) compounds were synthesized via solid-state reaction as a cathode material for IT-SOFC. The phase structure, electrical conductivity, oxygen transport performance, and the electrochemical performances of these compounds were evaluated. The as-prepared BCFx compounds show a single-phase perovskite structure. Among the BCFx materials, Bi_0.8Ca_0.2FeO_3–δ (BCF0.2) oxide has the maximum electrochemical catalytic activity. The polarization resistance of BCF0.2 cathode on symmetrical cell is 0.06 Ω·cm² at 750 ℃ in air. Meanwhile, the maximum peak power density of Ni-(Y₂O₃)_0.08(ZrO₂)_0.92(Ni-8YSZ) anode-supported single cell reaches 730 mW·cm² at 750 ℃ . As is indicated by the electrical conductivity relaxation, the favorable oxygen reduction reaction catalytic activity of BCF0.2 can be ascribed to the higher oxygen bulk diffusion and surface exchange coefficient. The results of oxygen reduction kinetics reveal that the dissociation of adsorbed molecular oxygen is a limiting step for oxygen reduction reaction on BCF0.2 cathode.