A novel cobalt-free Ba0.5Sr0.5Fe0.9Mo0.1O3−δ–BaZr0.1Ce0.7Y0.2O3−α composite cathode for solid oxide fuel cells

A new series of cobalt-free perovskite-type cathode materials Ba0.5Sr0.5Fe1−xMoxO3−δ (0 ≤ x ≤ 0.2) for proton conducting intermediate temperature solid oxide fuel cells (IT-SOFCs) are prepared by a citric-nitrate process. The conductivities of the cathode materials are measured as functions of temperature (300–800 °C) and oxygen partial pressure (1–10−10 atm). It is found that partial substitution of Mo for Fe site obviously enhances the conductivities of the cathode materials. Among the series of samples, Ba0.5Sr0.5Fe0.9Mo0.1O3−δ (BSFM10) has the highest conductivity to be 192 S cm−1 in air at 400 °C. The samples of 0 ≤ x ≤ 0.15 are p-type electronic conductors in the oxygen partial pressure range tested. An anode-supported BaZr0.1Ce0.7Y0.2O3−α (BZCY) electrolyte membrane is successfully fabricated by a simple, cost-effective spin coating process. Peak power densities of the hydrogen/air fuel cell using BZCY electrolyte membrane and BSFM10-BZCY composite cathode reach 153 mW cm−2 at 600 °C, 253 mW cm−2 at 650 °C and 420 mW cm−2 at 700 °C, respectively. The interfacial polarization resistance (Rp) for the fuel cell is as low as 0.15 Ω cm2 at 700 °C under open circuit conditions.

► A novel series of cobalt-free perovskite-type cathode materials Ba0.5Sr0.5Fe1−xMoxO3−δ (0 ≤ x ≤ 0.2) for proton conducting solid oxide fuel cells are prepared by a citric-nitrate process for the first time.
► It is found that partial substitution of Mo for Fe site obviously enhanced the conductivities of the cathode materials. Among the series of samples, the highest conductivity was observed for Ba0.5Sr0.5Fe0.9Mo0.1O3−δ (BSFM10) to be 192 S cm−1 in air at 400 °C.
► An anode-supported BaZr0.1Ce0.7Y0.2O3−α (BZCY) electrolyte membrane is successfully fabricated by a simple, cost-effective spin coating process.
► Peak power densities of the hydrogen/air fuel cell using BSFM10-BZCY composite cathode and BZCY electrolyte membrane reach 153 mW cm−2 at 600 °C, 253 mW cm−2 at 650 °C and 420 mW cm−2 at 700 °C, respectively.