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Hailei Zhao1 2 Zhihong Du1

1, University of Science and Technology Beijing, Beijing, , China
2, Beijing Municipal Key Lab for Advanced Energy Materials and Technologies, Beijing, , China

Over the past decade, significant efforts have been devoted to developing cost-effective and high-performance anode materials for solid oxide fuel cell (SOFC). Decorating the anode with highly catalytic catalyst nanoparticles and tailoring the crystal chemistry of anode materials are two main strategies to realize excellent performance of anode materials.
In this work, a series of double perovskites Sr2FeMo0.65M0.35O6 with outstanding performance are developed. Through in situ exsolution, several high performance anode materials, metallic nanoparticle catalysts decorated ceramics, were prepared from Sr2FeMo0.65M0.35O6 (SFMM, M = Co, Ni, Cu). The in situ reduction converts the pure perovskite phase into mixed phases containing Ruddlesden-Popper structure Sr3FeMoO7, perovskite SrFe1-yMoyO3 and metallic nanoparticle catalysts. The electrochemical performance of SFMCo and SFMNi ceramic anodes is greatly enhanced by the in situ exsolved Co-Fe and Ni-Fe alloy nanoparticle catalysts that homogenously distribute on the ceramic backbone surface. Owing to the catalytically inactive feature of Cu metal, the Cu nanofiber decorated SFMCu exhibits relatively poor anode performance. The maximum power densities of La0.8Sr0.2Ga0.8Mg0.2O3 electrolyte supported single cells with SFMCo and SFMNi anodes reach 820, and 960 mW cm-2 in wet H2 at 850 oC, respectively. The Sr2FeMo0.65Ni0.35O6 anode also shows excellent structural stability and good coking resistance in wet CH4. The prepared SFMCo and SFMNi materials are potential high performance anode for SOFC.
A novel double perovskite Sr2FeMo2/3Mg1/3O6-δ was designed and prepared as anode material for SOFCs. The structure study shows that the doped Mg actually takes the Fe-site, leading to the formation of a number of anti-site defects and the presence of FeB-O-FeB’ bonds. First-principles computation reveals that the presence of FeB-O-FeB’ bonds can promote the easy formation and fast migration of oxygen vacancies in the lattice, which are the key to affect the anode reaction kinetics. In an electrolyte (300 μm) supported single cell, the Sr2FeMo2/3Mg1/3O6-δ anode demonstrates excellent cell performance with maximum power density of 803, 1038 and 1316 mW cm-2 at 800, 850 and 900 oC, respectively. The Sr2FeMo2/3Mg1/3O6-d shows suitable thermal expansion coefficient (16.9 × 10-6 K-1), and good tolerance to carbon deposition and sulfur poisoning. The designed Sr2FeMo2/3Mg1/3O6-δ is an attractive anode material for SOFCs.

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