Evaluation of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ as a potential cathode for an anode-supported proton-conducting solid-oxide fuel cell

The potential application of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) as a cathode for a proton-conducting solid-oxide fuel cell based on BaCe_0.9Y_0.1O_2.95 (BCY) electrolyte was investigated. Cation diffusion from BCY to BSCF with the formation of a perovskite-type Ba²⁺-enriched BSCF and a Ba²⁺-deficient BCY at a firing temperature as low as 900 °C was observed, the higher the firing temperature the larger deviation of the A to B ratio from unit for the perovskites. Symmetric cell tests demonstrated the impurity phases did not induce a significant change of the cathodic polarization resistance, however, the ohmic resistance of the cell increased obviously. Anode-supported cells with the electrolyte thickness of ∼50 μm were successfully fabricated via a dual-dry pressing process for the single-cell test. Under optimized conditions, a maximum peak power density of ∼550 and 100 mW cm^-2 was achieved at 700 and 400 °C, respectively, for the cell with the BSCF cathode layer fired from 950 °C. At 500 °C, the ohmic resistance is still the main source of cell resistance. A further reduction in membrane thickness would envisage an increase in power density significantly.