Preparation and performance of Pr-doped Ba0.5Sr0.5Co0.8Fe0.2O3-δ cathode for IT-SOFCs

(Ba0.5Sr0.5)1-xPrxCo0.8Fe0.2O3-δ (BSPCFx; x=0.00-0.30) oxides were synthesized by a sol-gel thermolysis process using combination of PVA and urea, and were also investigated as cathode material for intermediate temperature solid oxide fuel cells(IT-SOFCs). X-ray diffraction (XRD) results showed that all the samples formed a single phase cubic pervoskite-type structure after being calcined at 950 °C for 5 h and the lattice constant decreased with the Pr content increasing. The electrical conductivity of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) was greatly enhanced by Pr- doping. The thermal expansion coefficient (TEC) of BSPCFx was increased with the content of Pr increasing, and all the thermal expansion curves had an inflection at about 250-400 °C due to the thermal-induced lattice oxygen loss and the reaction of Co and Fe ion. Ac impedance analysis indicated that BSPCFx possessed better electrochemical performance. The polarization resistance of the sample with x=0.2 was only ∼0.948 Ω cm2 at 500 °C, significantly lower than that of BSCF (∼2.488 Ω cm2).