A promising sol-gel route based on citric acid to synthesize Li3V2(PO4)3/carbon composite material for lithium ion batteries

Li3V2(PO4)3/carbon composite material was synthesized by a promising sol-gel route based on citric acid using V2O5 powder as a vanadium source. Citric acid acts not only as a chelating reagent but also as a carbon source, which enhance the conductivity of the composite material and hinder the growth of Li3V2(PO4)3 particles. The structure and morphology of the sample were characterized by TG, XRD and TEM measurements. XRD results reveal that Li3V2(PO4)3/carbon was successfully synthesized and has a monoclinic structure with space group P21/n. TEM images show Li3V2(PO4)3 particles are about 45nm in diameter embeded in carbon networks. Galvanostatic charge/discharge and cyclic voltammetry measurements were used to study its electrochemical behaviors which indicate the reversibility of the lithium extraction/insertion processes. Li3V2(PO4)3/carbon performed in a voltage window (3.0-4.8V) exhibits higher discharge capacity, better cycling stability and its discharge capacity maintains about 167.6mAh/g at a current density of 28mA/g after 50 cycles.