Synthesis of LiVPO4F with high electrochemical performance by sol-gel route

LiVPO4F was synthesized by a novel sol-gel method under Ar atmosphere using V2O5·nH2O, LiF, NH4H2PO4, and citric acid as starting materials, and its physicochemical properties were characterized using X-ray diffractometry (XRD), SEM, and electrochemical methods. The XRD patterns show that LiVPO4F displays a triclinic structure with a space group of p. The SEM results indicate that the particle size of LiVPO4F is about 0.8 μm together with homogenous distribution. The optimal sintering temperature and sintering time are 600 °C and 20 h, respectively, in order to obtain pure triclinic LiVPO4F with good electrochemical performance. LiVPO4F has the discharge capacity of 134 mA·h/g in the range of 3.0–4.4 V at the first cycle, and the discharge capacity remains 125 mA·h/g after 30 cycles. The sol-gel method is suitable for the preparation of LiVPO4F cathode materials with good electrochemical performance for lithium ion batteries.