Efficient Ferrite-Based Perovskite Anode for Solid Oxide Fuel Cells with A-Site and B-Site Co-exsolution

Exsolution of A-site and/or B-site dopants has been widely used to improve the electroactivity and coking resistance of the perovskite anode for solid oxide fuel cells (SOFCs). Here, an A-site and B-site co-exsolved Ba0.3Sr0.7Fe0.9Mn0.1O3-δ (BSFM) perovskite is employed as the anode material of SOFCs. X-ray diffraction results confirm that the cubic BSFM perovskite shows reasonable structure stability in hydrogen, although metallic Fe and SrO exsolve from the provskite lattice. Scanning electron microscopy results find that a whisker-like species grows from the perovskite in addition to the exsolution of Fe nanoparticles. It is verified by transmission electron microscopy-energy-dispersive X-ray spectroscopy that the whisker is composed of BaO and SrO. The surface enrichment of Ba and Sr elements is also proven by X-ray photoelectron spectroscopy. The peak power densities of a single cell with the BSFM anode are 538 and 364 mW cm-2 at 800 and 750 °C in hydrogen, respectively, while the polarization resistances of them are 0.18 and 0.28 ω cm2 at the same conditions, respectively. The cell operates stably for over 60 h in hydrogen with a current density of 0.2 A cm-2. However, the BSFM anode shows sluggish activity for methane oxidation. With the addition of Ni to the BSFM anode, its activity for methane oxidation is remarkably improved, and the peak power density increases from 84 mW cm-2 for the BSFM anode to 194 mW cm-2 for the Ni-BSFM anode at 800 °C in methane. The Ni-BSFM anode also exhibits excellent stability in methane and works stably for over 70 h with a current density of 0.2 A cm-2.