Synthesis and electrochemical performances of Li3V2(PO4)3/(Ag + C) composite cathode

Li3V2(PO4)3, Li3V2(PO4)3/C and Li3V2(PO4)3/(Ag + C) composites as cathodes for Li ion batteries are synthesized by carbon-thermal reduction (CTR) method and chemical plating reactions. The microstructure and morphology of the compounds are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Li3V2(PO4)3/(Ag + C) particles are 0.5–1 μm in diameters. As compared to Li3V2(PO4)3, Li3V2(PO4)3/C, the Li3V2(PO4)3/(Ag + C) composite cathode exhibits high discharge capacity, good cycle performance (140.5 mAh g−1 at 50th cycle at 1 C, 97.3% of initial discharge capacity) and rate behavior (120.5 mAh g−1 for initial discharge at 5 C) for the fully delithiated (3.0–4.8 V) state. Electrochemical impedance spectroscopy (EIS) measurements show that the carbon and silver co-modification decreases the charge transfer resistance of Li3V2(PO4)3/(Ag + C) cathode, and improves the conductivity and boosts the electrochemical performance of the electrode.