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

Abstract

The oxides SrMo1-xFexO3-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 Sr0.9Ba0.1Mo0.9Fe0.1O3-δ, in order to expand the unit-cell size and thereby improve the ionic diffusion of O2− ions through the crystal lattice. The anode materials must be stable under reducing conditions, since they work in the presence of the fuel (H2) at elevated temperatures. These anodes are inspired in the SrMoO3 perovskite, which contains Mo4+ 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/cm2 at 850 °C using pure H2 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. Keywords: IT-SOFC, Anode, Perovskite, Neutron diffraction, SrMoO3