Enhanced rate and cyclability of a porous Na3V2(PO4)(3) cathode using dimethyl ether as the electrolyte for application in sodium-ion batteries

Abstract

Sodium vanadium phosphate (NVP) is a potential cathode material for sodium-ion batteries, but its rate capability requires improvement. Herein, the electrode-electrolyte interface is modified using dimethyl ether (DME) electrolyte, such that the porous NVP cathode leads to ultrafast kinetics and ultra-long cycle life in comparison to those observed using conventional ethylene carbonate/propylene carbonate electrolytes. The rate capability and cycle life are the highest reported to date. The Na/NVP half-cell with DME affords good capacity (44 mA h g(-1) at 100 A g(-1); 854C) and stable ultra-long cycle life for 95 000 cycles with a negligible degradation rate (5.8 x 10(-5) % per cycle at 50 A g(-1), i.e., 1.05 Na+ reversibly reacts with NVP within 4.5 s). The NVP full cell coupled with a Sn anode delivers a reversible capacity of 70 mA h g(-1) at 10 A g(-1) for 5000 cycles with 100% coulombic efficiency. After 5000 cycles, the energy density is 217 W h kg(-1) and the power density is 30 985 W kg(-1) (based on NVP mass). The DME electrolyte effectively modifies the interface for fast kinetics both as a half-cell and a full cell. This simple strategy can be extended to other battery systems to achieve fast kinetics.