Effect of Mg-doping on electrochemical performance of PrBaFe₂O_5+δ cathode materials for solid oxide fuel cells

PrBaFe₂O_5+δ (PBF) is one of the promising cathode materials for intermediate-temperature solid oxide fuel cell (IT-SOFC) technology. However, as the operating temperature decreases, the electrochemical performance of this material deteriorates rapidly. To counter this, various doping strategies have been tested and reported in order to improve the electrochemical properties of this material at intermediate-temperatures. In this study, Mg-doping to partially substitute Fe of PBF was investigated. PrBaFe_2–xMg_xO_5+δ (PBFMg_x, x = 0.1, 0.15, 0.2, 0.3) materials were successfully synthesized, and their electrochemical performance as IT-SOFC cathode was evaluated. It is shown that Mg-doping enhances the conductivity of PBF between 650 and 800 °C, impacts little on the area-specific resistance of oxygen reduction reaction at and above 700 °C, and, most significantly, improves the power density of the Ni-SDC/SDC/PBFMg_0.15 single cell by 52% compared to the un-doped PBF. This enhanced electrochemical performance is attributed to the improvement in PBF conductivity by Mg-doping.