Li3V2(PO4)3/C composite as an intercalation-type anode material for lithium-ion batteries

The carbon coated monoclinic Li₃V₂(PO₄)₃ (LVP/C) powder is successfully synthesized by a carbothermal reduction method using crystal sugar as the carbon source. Its structure and physicochemical properties are investigated using X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy and electrochemical methods. The LVP/C electrode exhibits stable reversible capacities of 203 and 102 mAh g⁻¹ in the potential ranges of 3.0-0.0 V and 3.0-1.0 V versus Li⁺/Li, respectively. It is identified that the insertion/extraction of Li⁺ undergoes a series of two-phase transition processes between 3.0 and 1.6 V and a single phase process between 1.6 and 0.0 V. The ex situ XRD patterns of the electrodes at various lithiated states indicate that the monoclinic structure can still be retained during charge-discharge process and the insertion/deinsertion of lithium ions occur reversibly, which provides an excellent cycling stability with high energy efficiency.