Optimized energy conversion efficiency in solid-oxide fuel cells implementing SrMo1−xFexO3−δ perovskites as anodes

► Novel SrMo1−xFexO3−δ oxides are prepared and characterized by a number of techniques. ► Use of these oxides as anodes in SOFC doubles the performance of standard cermets. ► In situ neutron diffraction helps to understand the extraordinary performance: oxygen vacancies are created upon heating. Oxides of composition SrMo1−xFexO3−δ (x=0.1, 0.2) have been prepared, characterized and tested as anode materials in single solid-oxide fuel cells, yielding output powers close to 900mWcm−2 at 850°C with pure H2 as a fuel. This excellent performance is accounted for the results of an “in situ” neutron powder diffraction experiment, at the working temperature of the SOFC, showing the presence of a sufficiently high oxygen deficiency, with large displacement factors for oxygen atoms that suggest a large lability and mobility, combined with a huge metal-like electronic conductivity, as high as 340Scm−1 at T=50°C for x=0.1. The magnitude of the electronic conductivity decreases with increasing Fe-doping content. An adequate thermal expansion coefficient, reversibility upon cycling in oxidizing–reducing atmospheres and chemical compatibility with the electrolyte make these oxides good candidates for anodes in intermediate-temperature SOFC (IT-SOFCs).