NaVPO4F prepared under air as a cathode material for sodium-ion batteries

Abstract NaVPO 4 F with trivalent vanadium was successfully synthesized under air through controlling the appropriate heating/cooling rate and holding temperature after a hydrothermal process. The vanadium (III) in NaVPO 4 F can be facilely and successfully maintained even under air. As produced NaVPO 4 F has similar structure and cycle performance as the one prepared under argon protection. Even more excellent capability was exhibited when operating at high rate currents as cathode material for sodium-ion batteries. The effects of heat treatment atmosphere on electrochemical performances were evaluated by cycle performance, rate capability, and electrochemical impedance spectroscopy. NaVPO 4 F heated under air could offer a wider range of applications for sodium-ion batteries due to its facile synthesis and low cost.