Study on microstructure and physical properties of Ba0.5Sr0.5Fe1−xCuxO3−δ–Ce0.8Sm0.15Ca0.05O1.875 cathode materials used in solid oxide fuel cell

Abstract

Ba0.5Sr0.5Fe1−xCuxO3−δ (BSFCu) and BSFCu–Ce0.8Sm0.15Ca0.05O1.875 (SCDC) were prepared by solid-state reaction and sol-gel method, respectively. The possibility of BSFCu−SCDC composites as cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) was investigated. The results show that BSFCu has a cubic BaFeO3 structure and no secondary phase. BSFCu−SCDC has cubic BaFeO3 and Ce0.8Sm0.2O1.9 structures, and BaCeO3 secondary phase. The polarization surface specific resistance (ASRRP) of BSFCu increases with increasing Cu doping. For BSFCu–SCDC, 7BSFCu10–3SCDC has the smallest ASRRP (0.106 Ω cm2, 800 °C) at 800 °C–750 °C; at 600 °C − 700 °C, 6BSFCu10–4SCDC has the smallest ASRRP (1.043 Ω cm2, 600 °C). The maximum exchange current densities of 7BSFCu10–3SCDC and 6BSFCu10–4SCDC are about 0.219 and 0.083 A cm−2 at 800 °C and 700 °C, respectively. Compared with BSFCu, 6BSFCu10–4SCDC has a lower overpotential, which shows better electrocatalytic activity, so it can increase the energy efficiency when applied to IT-SOFC.