Carbon coated Li3V2(PO4)3 cathode material prepared by a PVA assisted sol-gel method

Carbon coated Li3V2(PO4)(3) cathode material was prepared by a poly(vinyl alcohol) (PVA) assisted sol-gel method. PVA was used both as the gelating agent and the carbon source. XRD analysis showed that the material was well crystallized. The particle size of the material was ranged between 200 and 500nm. HRTEM revealed that the material was covered by a uniform surface carbon layer with a thickness of 80 angstrom. The existence of surface carbon layer was further confirmed by Raman scattering. The electrochemical properties of the material were investigated by charge-discharge cycling, CV and EIS techniques. The material showed good cycling performance, which had a reversible discharge capacity of 100 mAh g(-1) when cycled at 1 C rate. The apparent Li+ diffusion coefficients of the material ranged between 9.5 X 10(-10) and 0.9 x 10(-10) cm(2) s(-1), which were larger than those of olivine LiFePO4. The large lithium diffusion coefficient of Li3V2(PO4)(3) has been attributed to its special NASICON-type structure. (C) 2010 Elsevier Ltd. All rights reserved.