Superior electrochemical properties of rutile VO₂-carbon composite microspheres as a promising anode material for lithium ion batteries

We report a new process to prepare VO₂(R)-carbon composite microspheres, which can be used as an anode material in lithium ion batteries. Crystalline V₂O₃-carbon composite microspheres prepared by a one-pot spray pyrolysis process are transformed into VO₂(R)-carbon composite microspheres by heat treatment at 300 °C under air atmosphere. Polyvinylpyrrolidone (PVP), which is used as the carbon source, affects the morphologies, crystal structures, and electrochemical properties of the vanadium oxide materials. The carbon content of the VO₂(R)-carbon composite powders is about 12.5 wt%. The bare vanadium oxide powders prepared from the spray solution without PVP show rod-like or spherical morphologies. The initial discharge and charge capacities of the VO₂(R)-carbon composite powders are 1091 and 659 mA h g⁻¹, respectively. The discharge capacity of the VO₂(R)-carbon composite powders after 100 cycles is 637 mA h g⁻¹ and their capacity retention after 100 cycles measured from the second cycle is 96.0%. The high structural stability encountered during lithium insertion and extraction improves the electrochemical properties of the VO₂(R)-carbon composite powders