Alleviating the stability-energy density dilemma via electron-donor-mediated orbital symmetry regulation in sodium phosphate cathodes

Manganese-based sodium super ionic conductor-type cathode materials, leveraging the multielectron redox activity of manganese, represent a promising pathway toward high-energy-density sodium-ion batteries (SIBs). However, the unavoidable generation of Mn 3+ (3d 4 ) species during charge-discharge processes, characterized by asymmetric e g orbital occupancy, triggers octahedral symmetry breaking. This inherent electronic structural instability creates a fundamental contradiction between achieving high energy density and ensuring long cycle life that remains inherently difficult to reconcile. Here, we report an electron-donor–mediated (EDM) mechanism that suppresses Mn 3+ -induced octahedral distortion while preserving high-spin functionality. As electron-donating Fe 3+ and V 3+ are incorporated, Mn 3+ 3d electrons undergo partial delocalization. This electronic redistribution promotes orbital interactions between neighboring transition metal sites through the transition metal-oxygen framework, driving the e g orbitals toward a more symmetric occupation and suppressing octahedral distortion. The EDM-modified cathode demonstrates a high energy density of 492.06 Wh kg −1 . It delivers 178.8 mAh g −1 at 0.1 C and retains 80.2% of its capacity over 2000 cycles at 10 C, paving a novel pathway toward next-generation high-performance SIBs cathode materials.