SmBa0.5Sr0.5CoCuO5+δ and Sm0.5Ba0.25Sr0.25Co0.5Cu0.5O3-δ oxygen electrode materials for Solid Oxide Fuel Cells: Crystal structure and morphology influence on the electrocatalytic activity

The influence of the material's crystal structure and morphology of the electrode layer on the electrocatalytic activity toward the oxygen reduction reaction is studied for the selected perovskite-type oxygen electrode materials for Solid Oxide Fuel Cells. The A-site cation-disordered Sm0.5Ba0.25Sr0.25Co0.5Cu0.5O3-δ with Pm-3 m cubic perovskite, obtained previously by the electrospinning method (ES), and compound with the same ratio of cations, the A-site cation-ordered SmBa0.5Sr0.5CoCuO5+δ, prepared by a typical sol-gel route (SG), P4/mmm double perovskite are considered. It is documented that both compounds differ in their basic physicochemical properties, while the ES-based electrode layer shows higher electrocatalytic activity, and exhibits improved long-term stability. The reasons behind the enhancement are uncovered, with i.a. distribution of relaxation times analyses enabling a deeper insight into the attained modifications. It is found that better performance of the ES electrode cannot be solely explained as due to the changed morphological features, but stems also from the altered physicochemical properties of the active material. The developed ES electrode exhibits the polarization resistance of 0.18 Ω cm2 at 700 °C, and 0.04 Ω cm2 at 800 °C, which is ca. four times lower in comparison to the SG-based one. Also, for an anode-supported cell, the registered power density output is over 260 mW cm−2 at 700 °C, and close to 400 mW cm−2 at 750 °C.