Sr-doping induces lattice modulation in perovskite for enhanced reversible solid oxide cell performance

The increasing demand for sustainable energy urgently requires efficient reversible power-to-X conversion technologies, for which Reversible Solid Oxide Cells (RSOCs) represent a transformative solution. Nonetheless, their practical deployment has been hindered by the inadequate activity and poor long-term stability of oxygen electrodes. Herein, a novel double perovskite, Nd 0.6 Sr 0·4 BaCo 1·6 Fe 0·4 O 5+δ , was designed as an oxygen electrode, featuring an A-site Sr-doping strategy that induces lattice modulation with optimized electronic structure and ionic transport pathways. The Nd 0.6 Sr 0·4 BaCo 1·6 Fe 0·4 O 5+δ cell demonstrated outstanding RSOCs performance, which achieved peak power density of a 1.44 W cm −2 (800 °C) in Solid Oxide Fuel Cell (SOFC) mode and an electrolysis current density of 1.62 A cm −2 at 1.3 V in Solid Oxide Electrolysis Cell (SOEC) mode, representing increases of 51% and 45%, respectively, compared to Sr-free sample. At 750 °C, the 100 cm 2 cell further demonstrated its exceptional scalability, delivering 68 W (SOFC) output and 131 W (SOEC) input power at 1.3 V with 120 h stable operation and no significant degradation (degradation rate of 0.028% h -1 ). Combining X-ray absorption fine structure (XAFS) analysis and Density Functional Theory (DFT) revealed that Sr-doping effectively modulates valence and spin states of Co and Fe, inducing CoO 6 octahedral distortions with shortened Co-O bonds and elongated Co-M bonds. These structural modifications not only enhance the framework stability of Nd 0.6 Sr 0·4 BaCo 1·6 Fe 0·4 O 5+δ but also create supplementary oxygen migration pathways in it, thereby boosting its electrocatalytic activity. These findings verify the excellent electrocatalytic activity, durability, and scalable manufacturability of this material, highlighting its strong potential for practical RSOCs applications.