Na+ doping activates and stabilizes layered perovskite cathodes for high-performance fuel cells

A highly active mixed conductive cathode is required for solid oxide fuel cells (SOFCs) based on yttria-stabilized zirconia (YSZ) at reduced temperatures, which is one of the most important factors for their commercialization. Herein, we propose a Na+ doping strategy to activate and stabilize the triple-conducting (H+/O2−/e−) layered perovskite oxide of representative NdBa0.5Sr0.5Co1.5Fe0.5O5+δ (NBSCF) for high-performance YSZ fuel cells. The results show that Na+ doping enhances the electrochemical properties of the NBSCF cathode, with polarization impedance decreasing from 0.105 to 0.080 Ω cm2 at 750 °C and output power increasing from 946.05 to 1435.75 mW cm−2 at 800 °C. Furthermore, high-temperature XRD (HT-XRD) and the oxygen temperature-programmed desorption (O2-TPD) further confirm that Na+ doping can improve the structural stability of NBSCF. The single cell with a Na-doped NBSCF cathode showed no degradation of current density for more than 120 h at 700 °C and exhibited good stability. This work demonstrates the promise of Na+ doping for layered perovskite cathodes and an effective way to promote fuel cell performance.