Preparation and characterization of Pr_2-xSr_xCoO_4+δ cathode materials for IT-SOFC

The samples of Pr_2-xSr_xCoO_4+δ (x=0.8, 1.0, 1.2) as cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC) were synthesized by solid-state reaction. Crystal structure, thermal expansion, electrical conductivity and electrochemical properties were investigated by XRD, SEM, dilatometry, DC four-probe method, AC impedance and cyclic voltammetry (CV) techniques, respectively. The XRD results showed all the samples obtained as a single K₂NiF₄-structural phase, there were no chemical reaction occurred between the Pr_0.8Sr_1.2CoO_4+δ electrode and the Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte at 1100°C in air. The thermal expansion coefficients (TECs) increased with Sr content increasing. The electrical conductivity of the specimens was over 100 S/cm at 800°C. The polarization resistance decreased with the increasing of Sr content. Pr_0.8Sr_1.2O_4+δ had the optimum value of 0.29 Ω · cm² at 700°C in air.