Exceptionally High Performance Anode Material Based on Lattice Structure Decorated Double Perovskite Sr_2FeMo_(2/3)Mg_(1/3)O_(6−δ) for Solid Oxide Fuel Cells

摘要

A novel double perovskite Sr2FeMo2/3Mg1/3O6-delta is prepared and characterized as an anode material for solid oxide fuel cells (SOFCs). X-ray diffraction refinement reveals that Mg and Mo cations locate separately in two different B sites (B and B' in A(2)BB'O-6) while Fe occupies both B and B' sites, forming the lattice structure with the form of Sr-2(Mg1/3Fe2/3)(Mo2/3Fe1/3)O6-delta. The inactive element Mg doping not only endows the material with excellent redox structural stability but also triggers the creation of antisite defects in the crystal lattice, which provide the material with excellent electrochemical activity. The anode performance of Sr2FeMo2/3Mg1/3O6-d is characterized in an La0.8Sr0.2Ga0.8Mg0.2O3-delta electrolyte supported cell with La0.58Sr0.4Fe0.8Co0.2O3-delta cathode. A peak power density of 531, 803, 1038, and 1316 mW cm(-2) at 750, 800, 850, and 900 degrees C, respectively, is achieved in humidified H-2. The Sr2FeMo2/3Mg1/3O6-delta shows suitable thermal expansion coefficient (16.9(2) x 10(-6) K-1), high electrical conductivity, and good tolerance to carbon deposition and sulfur poisoning. Firstprinciple computations demonstrate that the presence of Fe-B-O-Fe-B' bonds can promote the easy formation and fast migration of oxygen vacancies in the lattice, which are the key to affecting the anode reaction kinetics. The excellent overall performance of Sr2FeMo2/3Mg1/3O6-delta compound makes it a promising anode material for SOFCs.