Highly efficient and stable intermediate-temperature solid oxide fuel cells using Bi-deficient perovskite cathode

Abstract

Herein, we develop Bi-efficient Sr-free perovskite as the cathode toward highly efficient and stable intermediate-temperature SOFCs, and illustrate the important role of Bi-vacancy in boosting their activity and durability. The optimized La0.6Bi0.3Co0.2Fe0.8O3−δ (L0.6B0.3CF) with partial Bi-vacancy presents an area-specific resistance of ∼0.0329 Ω cm2 at 800 °C. The assembled anode-supported single cell with L0.6B0.3CF as cathode shows excellent peak power densities (∼1.35W cm−2 at 800 °C). Importantly, this single cell with L0.6B0.3CF cathode exhibits superior stability, owing to the effective suppression of Bi depletion and the well matched thermal expansion coefficient (8.9 × 10−6 K−1) with the typical electrolytes. Combined with the first-principles calculations, we revealed that Bi-defect would directly impact on the stoichiometry of oxygen and on the valence states of the transition-metal ions. Our results may provide a new insight for the design of highly efficient and stable cathode materials in SOFCs.