High-rate capability of Li3V2(PO4)3/C composites prepared via a polyvinylpyrrolidone-assisted sol-gel method

Carbon-coated monoclinic Li3V2(PO4)(3)/C (LVP/C) cathode materials are successfully prepared via a polyvinylpyrrolidone (PVP)-assisted sol-gel method. LVP/C composites are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and electrochemical methods. The results indicate that the sample synthesized with 9 wt% PVP is coated with a carbon layer in a thickness of about 12 nm, which presents excellent rate capability and good cyclic performance. In the potential range of 3.0-4.3 V. it shows a capacity of 127.2 and 115.1 mAh g(-1) at 1 and 10 C, respectively. Even at discharge rate of 20 C. it still has 81.8 mAh g(-1) with 10.7% capacity loss after 120 cycles. The lithium diffusion coefficient of the as-prepared material is in the order of 10(-8) cm(2) s(-1). Our experiment results demonstrate that the LVP/C composites prepared via a PVP-assisted sol-gel method can be an attractive candidate as cathode materials in high-power lithium-ion batteries. (C) 2012 Elsevier B.V. All rights reserved.