A novel anions and cations co-doped strategy for developing high-performance cobalt-free cathode for intermediate-temperature proton-conducting solid oxide fuel cells

Abstract The sluggish activity of cathode at intermediate-temperature limits commercialization of proton-conducting solid oxide fuel cells (H-SOFCs). In this investigation, a novel cathode of Ba 0.95 Ca 0.05 Fe 0.85 Sn 0.05 Y 0.1 O 2.9−δ F 0.1 was successfully developed by co-doping of anion F and cations Ca, Sn, Y. We studied the effect of F − -doping on phase structure, electrical conductivity and electrochemical properties of the cell. Compared with Ba 0.95 Ca 0.05 Fe 0.85 Sn 0.05 Y 0.1 O 3−δ , F − -doped Ba 0.95 Ca 0.05 Fe 0.85 Sn 0.05 Y 0.1 O 3−δ exhibited higher conductivity. Composite cathode consisting of Ba 0.95 Ca 0.05 Fe 0.85 Sn 0.05 Y 0.1 O 2.9−δ F 0.1 and Sm 0.2 Ce 0.8 O 2−δ was applied in H-SOFCs with BaZr 0.1 Ce 0.7 Y 0.2 O 3−δ electrolyte which achieves an encouraging performance with the maximum power density of 1050 mW cm −2 and polarization resistance of 0.04 Ω cm 2 at 700 °C. The result of First-principles calculations based on spin-polarized Density Functional Theory shows that doping of F − reduces the activation energy required for migration of oxygen ions. These results demonstrate that the anions and cations co-doped strategy can provide a new horizon for the cathode in H-SOFCs.