Design, synthesis and performance of Ba-doped derivatives of SrMo0.9Fe0.1O3-δ perovskite as anode materials in SOFCs

The oxides SrMo 1-x Fe x O 3-δ (x = 0.1 and 0.2) have recently been described as excellent anode materials for solid-oxide fuel cells at intermediate temperatures (IT-SOFC) with LSGM as the electrolyte. In this work we have partially replaced Sr by Ba in a compound of formula Sr 0.9 Ba 0.1 Mo 0.9 Fe 0.1 O 3-δ , in order to expand the unit-cell size and thereby improve the ionic diffusion of O 2− ions through the crystal lattice. The anode materials must be stable under reducing conditions, since they work in the presence of the fuel (H 2 ) at elevated temperatures. These anodes are inspired in the SrMoO 3 perovskite, which contains Mo 4+ ions, stable in very reducing conditions. This novel oxide has been structurally characterized from x-ray (XRD) and neutron powder diffraction (NPD) data; the structure is defined at room temperature in the Pm-3m space group, and shows oxygen vacancies, necessary for the performance of this material as mixed ionic-electronic (MIEC) oxide. In single test cells supported on LSGM, the materials generated output powers close to 500 mW/cm 2 at 850 °C using pure H 2 as fuel. The thermal expansion is linear, with TEC = 10.93 × 10 −6 K −1 . The chemical compatibility with the LSGM electrolyte was also verified.