Suppressed the High-Voltage Phase Transition of P2-Type Oxide Cathode for High-Performance Sodium-Ion Batteries.

Sodium-ion batteries (SIBs), using the resourceful Mn-based materials as cathodes, have been considered as promising candidates for large-scale energy-storage applications. However, the representative P2-type Mn-based layered oxide cathode usually suffers from a limited specific capacity and a poor cycle life in Na-ion intercalation and deintercalation processes because of the unavoidable phase transition at a high voltage. Herein, we developed Ru-substituted P2-Na0.6MnO2 as a promising sodium host with a high reversible capacity and cycle life. The multiple characterization investigations reveal that Ru substitution could improve the electronic and ionic conductions and particularly suppress the phase transition of P2-OP4, resulting in the extension of the single-phase reaction region. Ru substitution not only enhances the specific capacity (209.3 mA h g-1) but also improves the rate capability (∼100 mA h g-1 at 50 C) and cycling stability. This work may open a new avenue for designing and fabricating SIBs by using Mn-based cathodes with high capacity and stability.