One-pot synthesis of carbon-coated VO2(B) nanobelts for high-rate lithium storage

Abstract

Uniform carbon-coated single crystalline vanadium dioxide (VO₂(B)@C) nanobelts were successfully prepared by using a facile one-pot hydrothermal approach. Sucrose plays a dual role in this hydrothermal process, namely as a carbon precursor for the carbon shell and, as a reductant to reduce V₂O₅ to VO₂(B). The thickness of the carbon coating layer is tunable from 3.0 to 6.9 nm by changing the ratio of the precursors. Although a high carbon content can improve the electrical conductivity of VO₂(B)@C nanobelts, a thick carbon coating layer would block the lithium ion diffusion. The optimal thickness is found to be 4.3 nm (carbon content: 6.6 wt%), where the cathode displays superior performance with highly reversible specific capacities, good cycling stabilities and excellent rate capabilities (e.g. 100 mA h g⁻¹ at 12.4 C).