Study on synthesis routes and their influences on chemical and electrochemical performances of Li3V2(PO4)3/carbon

In this study, Li₃V₂(PO₄)₃/carbon samples were synthesized by two different synthesis routes. Their influence on chemical and electrochemical performances of Li₃V₂(PO₄)₃/carbon as cathode materials for lithium-ion batteries was investigated. The structure and morphology of Li₃V₂(PO₄)₃/carbon were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM) measurements. TEM revealed that the Li₃V₂(PO₄)₃ grains synthesized through the sol-gel route had a depressed grain size. Electrochemical behaviors were characterized by galvanostatic charge/discharge, cyclic voltammetry and AC impedance measurements. Li₃V₂(PO₄)₃/carbon with smaller grain size showed better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of the Li₃V₂(PO₄)₃/carbon were attributed to the depressed grain size and enhanced electrical contacts produced via the sol-gel route. AC impedance measurements also showed that the sol-gel route significantly decreased the charge-transfer resistance and shortened the migration distance of lithium ion.