One-Step Synthesis of Carbon-Coated Na-3(VOPO4)(2)F Using Biomass as a Reducing Agent and Their Electrochemical Properties

In this work, a one-step hydrothermal strategy has been developed for the synthesis of carbon-coated Na-3(VOPO4)(2)F with the aid of biomass (e.g. glucose, fructose or starch), where biomass plays the key role of carbon source and reducing agent for reducing vanadium(V) to vanadium(IV). The effect of different biomass on the morphologies has been examined. Furthermore, the synthetic mechanism was deduced by investigating the impact of hydrothermal time on the synthesis. In addition, the vanadium oxidation state has been finally confirmed by XPS and UV-Vis. The as-synthesized carbon-coated Na-3(VOPO4)(2)F shows a superior long-term cycling performance, such as the capacity retentions are higher than 70% after 1400 cycles at a current rate of 5 C. The higher content of carbon will lead to the better rate capability. The present study suggests that the one-step hydrothermal technique using biomass as a reducing agent appears to be a facile and green low-cost approach to prepare the promising cathode material Na-3(VOPO4)(2)F.