Synthesis and characterization of carbon-coated Li3V2(PO4)3 cathode materials with different carbon sources

The carbon-coated monoclinic Li3V2(PO4)(3) (LVP) cathode materials were synthesized by a solid-state reaction process under the same conditions using citric acid, glucose, PVDF and starch, respectively, as both reduction agents and carbon coating sources. The carbon coating can enhance the conductivity of the composite materials and hinder the growth of Li3V2(PO4)(3) particles. Their structures and physicochemical properties were investigated using X-ray diffraction (XRD), thermogravimetric (TG), scanning electron microscopy (SEM) and electrochemical methods. In the voltage region of 3.0-4.3 V, the electrochemical cycling of these LVP/C electrodes all presents good rate capability and excellent cycle stability. It is found that the citric acid-derived LVP owns the largest reversible capacity of 118 mAh g(-1) with no capacity fading during 100 cycles at the rate of 0.2C, and the PVDF-derived LVP possesses a capacity of 95 mAh g(-1) even at the rate of 5C While in the voltage region of 3.0-4.8V, all samples exhibit a slightly poorer cycle performance with the capacity retention of about 86% after 50 cycles at the rate of 0.2C. The reasons for electrochemical performance of the carbon coated Li3V2(PO4)(3) composites are also discussed. The solid-state reaction is feasible for the preparation of the carbon coated Li3V2(PO4)(3) composites which can offer favorable properties for commercial applications. (C) 2009 Elsevier Ltd. All rights reserved.