Preparation and characterization of Pr_1-xSr_xFeO₃ cathode material for intermediate temperature solid oxide fuel cells

A kind of cathode material of Pr_1-xSr_x FeO₃ (x = 0-0.5) for intermediate temperature solid oxide fuel cells (IT-SOFCs) was prepared by the coprecipitation method. Crystal structure, thermal expansion, electrical conductivity and electrochemical performance of the Pr_1-xSr_xFeO₃ perovskite oxide cathodes were studied by different methods. The results revealed that Pr_l-xSr_xFeO₃ exhibited similar orthorhombic structure from x = 0.1 to 0.3 and took cubic structure when x = 0.4-0.5. The unit cell volume decreased and the thermal expansion coefficient (TEC) of the materials increased as the strontium content increased. When 0 < x ≤ 0.3, the samples exhibited good thermal expansion compatibility with YSZ electrolyte. The electrical conductivity increased with the increasing of doped strontium content. When x = 0.3-0.5, the electrical conductivities were higher than 100 S cm^-1. The conductivity of Pr_0.8Sr_0.2FeO₃ was 78 S cm^-1 at 800 °C. Compared with the La_0.8Sr_0.2MnO₃ cathode, Pr_0.8Sr_0.2FeO₃ showed higher polarization current density and lower polarization resistance (0.2038 Ω cm²). The value of I₀ for Pr_0.8Sr_0.2FeO₃ at 800 °C is 123.6 mA cm^-2. It is higher than that of La_0.8Sr_0.2MnO₃. Therefore, Pr_1-xSr_xFeO₃ can be considered as a candidate cathode material for IT-SOFCs.