Cobalt-free Ba_0.5Sr_0.5Fe_0.8Cu_0.1Ti_0.1O_3-δ as a bi-functional electrode material for solid oxide fuel cells

In this study, we investigate a cobalt-free titanium-doped perovskite oxide with the nominal composition of Ba_0.5Sr_0.5Fe_0.8Cu_0.1Ti_0.1O_3-δ (BSFCuTi) as a potential electrode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). In comparison to Ba_0.5Sr_0.5Fe_0.9Cu_0.1O_3-δ, BSFCuTi exhibits improved phase stability and a reduced thermal expansion coefficient even though the electrical conductivity decreases. A low area specific resistance of 0.088 Ω cm² is achieved at 600 °C based on a symmetrical cell test, which is comparable to the result for the benchmark Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ cobalt-based perovskite electrocatalyst. Stable operation for a period of 200 h is also demonstrated. The I-V test shows a very high power output of 1.16 W cm^-2 for a single cell using a BSFCuTi cathode at 600 °C. In addition, the BSFCuTi can be partially reduced under a reducing atmosphere to prepare a suitable anode material. A cell with BSFCuTi as the material for both electrodes and a thick Gd_0.2Ce_0.8O_1.9 electrolyte (300 μm) delivers an attractive power density of 480 mW cm^-2 at 800 °C. The high activity, favorable stability and bi-functionality make BSFCuTi a promising electrode material for IT-SOFCs.