Evaluation of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) as a potential cathode for an anode-supported proton-conducting solid-oxide fuel cell

摘要

The potential application of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSCF) as a cathode for a proton-conducting solid-oxide fuel cell based on BaCe_(0.9)Y_(0.1)O_(2.95) (BCY) electrolyte was investigated. Cation diffusion from BCY to BSCF with the formation of a perovskite-type Ba~(2+)-enriched BSCF and a Ba~(2+)-deficient BCY at a firing temperature as low as 900 ℃ 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 ℃, respectively, for the cell with the BSCF cathode layer fired from 950 ℃. At 500 ℃, 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.