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International audience; This paper reports impedance studies of a dual membrane fuel cell - an innovative design based on the idea for a junction between an oxygen ion conducting cathode/electrolyte part and proton conducting anode/electrolyte part through a mixed oxygen ion and proton conducting porous membrane. Thus oxygen, hydrogen and water are located in three independent chambers. This concept allows avoiding all the severe pitfalls connected to the presence of water at electrodes in both SOFC and PCFC. The performed measurements of the 3 compartments and the data analysis are improved by introducing some specialized approaches and techniques, which are discussed. The impedance contribution in the proof of the new concept is also presented.

The acceptor-substituted BaSn0.875M0.125O3-δ (M = Sc, In, Y, and Gd) proton conductors were prepared by a wet chemical method. The effects of dopant nature on the structure, hydration energy and proton conduction have been investigated. Analysis of XRD data showed that all compounds present a cubic perovskite structure (space group: P m 3 − m ). Thermogravimetry analysis showed that the significant mass of water was gained in wet Ar during measurements, and the most negative hydration energy is observed for Sc-substituted BaSnO3 (−86 kJ/mol). However, Y-substituted BaSnO3 exhibits the highest proton conductivity at low temperature under wet Ar, such as the total conductivity is 4.8 × 10−4 S/cm at 600 °C.

The structural, dynamical and dielectric properties of the cubic phase of perovskite barium stannate BaSnO3, a potential candidate as protonic conductor for solid oxide fuel cells, have been investigated by the means of first-principles density functional calculations, and the structural and electrical properties have been explored at low temperature. From density functional perturbative calculations, the phonon modes, the Born effective charges and the dielectric tensor are derived and analyzed, at zero pressure. The phonon band-structure of the cubic phase does not exhibit unstable modes, in good agreement with x-ray diffraction, which shows that BaSnO3 remains perfectly cubic down to 10 K. The dielectric response in BaSnO3 as measured and calculated is lower than in titanate and zirconate perovskites.