Development and Investigation of a NASICON-Type High-Voltage Cathode Material for High-Power Sodium-Ion Batteries.

Herein, we introduce a 4.0 V class high-voltage cathode material with a newly recognized sodium superionic conductor (NASICON)-type structure with cubic symmetry (space group P2 3), Na V(PO ) N. We synthesize an N-doped graphene oxide-wrapped Na V(PO ) N composite with a uniform carbon coating layer, which shows excellent rate performance and outstanding cycling stability. Its air/water stability and all-climate performance were carefully investigated. A near-zero volume change (ca. 0.40 %) was observed for the first time based on in situ synchrotron X-ray diffraction, and the in situ X-ray absorption spectra revealed the V /V redox reaction with high reversibility. Its 3D sodium diffusion pathways were demonstrated with distinctive low energy barriers. Our results indicate that this high-voltage NASICON-type Na V(PO ) N composite is a competitive cathode material for sodium-ion batteries and will receive more attention and studies in the future.