Ba0.9Co0.7Fe0.2Nb0.1O3-δ perovskite as promising cathode material for proton ceramic fuel cell

The protonic ceramic fuel cell (PCFC) is limited in performance by the delayed oxygen reaction on the cathode caused by low temperature. Herein, we investigate Ba0.9Co0.7Fe0.2Nb0.1O3-δ (BCFN), a cathode material with excellent electrocatalytic activity and structural stability. The electrical conductivity relaxation method was explored for the proton transport ability of BCFN material, which revealed a proton diffusion coefficient of 0.515 × 10−3 cm s−1 at 600 °C. To further enhance the proton conductivity of material and increase the reaction sites, a BCFN-BaCe0.7Zr0.1Y0.1Yb0.1O3−δ (BCZYYb) composite cathode was developed and its average thermal expansion coefficient value was lowered to 15.7 × 10−6 K−1 from 30 to 800 °C. At 700 °C, a single cell with a BCFN-BCZYYb cathode achieves a peak power density of 859 mW cm−2, and the Rp value is 0.05 Ω cm2. Furthermore, good durability of stable operation at 150 mA cm−2 for 100 h is obtained at 600 °C. These results imply that BCFN-BCZYYb could be an effective PCFC cathode.