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

NaVPO4F 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 NaVPO4F can be facilely and successfully maintained even under air. As produced NaVPO4F 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. NaVPO4F heated under air could offer a wider range of applications for sodium-ion batteries due to its facile synthesis and low cost.