Rationally Designed Sodium Chromium Vanadium Phosphate Cathodes with Multi?Electron Reaction for Fast?Charging Sodium?Ion Batteries

Sodium super-ionic conductor (NASICON)-structured phosphates are emerging as rising stars cathodes for sodium-ion batteries. However, they usually suffer from a relatively low capacity due to the limited activated redox couples and intrinsic electronic conductivity. Herein, reduced graphene oxide supported NASICON Na3Cr0.5V1.5(PO4)3 cathode (VC/C-G) is designed, which displays ultrafast (up 50 C) ultrastable (1 000 cycles at 20 Na+ storage properties. The VC/C-G can reach high energy density of ?470 W h kg?1 0.2 C with specific 176 mAh g?1 (equivalent theoretical value); this corresponds three-electron transfer reaction based on fully V5+/V4+, V4+/V3+, V3+/V2+ couples. In situ X-ray diffraction (XRD) results disclose combination solid-solution biphasic mechanisms upon cycling. Density functional theory calculations reveal narrow forbidden-band gap 1.41 eV diffusion barrier 0.194 eV. Furthermore, shows excellent fast-charging performance by only taking ?11 min 80% state charge. work provides widely applicable strategy realizing multi-electron design high-performance SIBs.