An intermediate temperature fuel cell based on composite electrolyte of carbonate and doped barium cerate with SrFe0.7Mn0.2Mo0.1O3−δ cathode

•New oxide SrFe0.7Mn0.2Mo0.1O3−δ was synthesized as cathode for ITFCs.•BaCe0.5Zr0.3Y0.16Zn0.04O3−δ and carbonates react to form BaCO3 and oxides.•SrFe0.7Mn0.2Mo0.1O3−δ is not compatible with carbonates forming SrCO3.•Doped CeO2 is a better choice for oxide–carbonate composite electrolyte.

BaCeO3-based proton conductor BaCe0.5Zr0.3Y0.16Zn0.04O3−δ (BCZYZn) was adopted as a part of the oxide-carbonate composite electrolyte. The total ionic conductivity of BCZYZn-carbonate composite is 0.28 S cm−1 at 500 °C. Perovskite oxide SrFe0.7Mn0.2Mo0.1O3−δ was developed and used as cathode. It was found that SrFe0.7Mn0.2Mo0.1O3−δ exhibits a primitive cubic structure with space group Pm3¯m(221); a = 3.8790(1) Å, V = 58.364(1) Å3. The electrical conductivity of SrFe0.7Mn0.2Mo0.1O3−δ is 15–26 S cm−1 in the temperature range 400–700 °C measured by d.c. method. Single cell with BCZYZn-carbonate composite electrolyte and SrFe0.7Mn0.2Mo0.1O3−δ cathode was fabricated and tested with humidified H2 (∼3 vol% H2O) as fuel and air as oxidant. A similar configuration cell with lithiated NiO cathode was also constructed for comparison. It was found that neither BaCe0.5Zr0.3Y0.16Zn0.04O3−δ nor SrFe0.7Mn0.2Mo0.1O3−δ is chemically compatible with (Li,Na)2CO3. The fuel cell performance is not as good as those based on doped ceria-carbonate electrolytes.