Preparation and electrochemical performance of rechargeable lithium battery LiVPO4F cathode material

A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were preheated at 300 degrees C and reacted at 750 degrees C under an inert atmosphere to yield the trivalent vanadium phosphate VPO4. In the second step, the product LiVPO4F was synthesized by the reaction with VPO4 and LiF. The LiVPO4F was characterized by X-ray diffraction, scanning electron microscopy, cyclic voltammetry and charge/discharge testing measurements. The LIVPO4F is triclinic crystalline system. At 0.1 C rate, the first charge/discharge capacities were 150.1 mAh-g(-1) and 132.6 mAh-g(-1); At 0.2 C rate, the first charge/discharge capacities were 142.9 mAh-g(-1) and 125.2 mAh-g(-1). The LiVPO4F from this work has higher charge/discharge voltage 4.3 V and 4.1 V, respectively.