Synthesis of graphene-modified Li3V2(PO4)3 with superior electrochemical properties via a catalytic solid-state-reaction process

A graphene-coated Li3V2(PO4)3 (LVP) powder (LVP@G) is synthesized via a two-step solid-state-reaction process. The graphene is converted in-situ from polyvinyl alcohol (PVA) or citric acid as a carbon source with the VOx-containing intermediate product as a catalyst. The results of two carbon sources (PVA and citric acid) are compared. X-ray diffraction, scanning/transmission electron microscopy and Raman spectroscopy are employed to study the compositions and structures. Cyclic voltammetry, galvanostatic cell cycling and electrochemical impedance spectroscopy are used to characterize the electrochemical performances. It is found that citric acid as a comparative carbon source leads to less amount of carbon residue than PVA. Also, the degree of graphitization of the carbon from citric acid is smaller than that from PVA. The LVP@G formed with PVA as the carbon source delivers a superb rate electrochemical performance with discharge capacity of 112.7 mAh·g−1 at 20C rate in the voltage range of 3.0-4.8 V.