Highly active cobalt-free perovskites with Bi doping as bifunctional oxygen electrodes for solid oxide cells

[Display omitted] •A cobalt-free bifunctional oxygen electrode PBSM is developed for reversible SOCs.•Bi doping in the perovskite significantly increases oxygen transport kinetics.•PBSM is directly applied to the interlayer-free YSZ electrolyte-based cells.•SOCs with PBSM exhibit record high electrochemical performance. Cobalt-containing perovskite materials have been intensively investigated as bifunctional oxygen electrodes for solid oxide cells because of their mixed ionic-electronic conducting nature. However, the direct application of these materials to the most widely used zirconia-based electrolytes has been limited because of their thermo-chemical incompatibility. Herein, we introduce a cobalt-free manganite-perovskite with significantly improved electrocatalytic activity by doping with Bi which possesses stereochemically active lone pair electrons. Replacing Bi with Pr in Pr0.8Sr0.2MnO3−δ increases the oxygen vacancy concentration and promotes oxygen ion incorporation and charge transfer processes at the electrode. Consequently, we apply Pr0.5Bi0.3Sr0.2MnO3−δ, to the interlayer-free yttria-stabilized zirconia electrolyte-based cells, which exhibits record high performance in the fuel cell (1.91 W∙cm−2) as well as electrolysis (1.90 A∙cm−2) modes at 700 °C along with remarkable long-term stability (450 h). Thus, our findings demonstrate that Pr0.5Bi0.3Sr0.2MnO3−δ is a highly promising bifunctional catalyst for solid-state energy storage and conversion applications.