Fabrication of VO Nanorings on a Porous Carbon Architecture for High-Performance Li-Ion Batteries.

ABSTRACT

Vanadium monoxide (VO) is a promising candidate as an anode for lithium-ion batteries due to its high theoretical capacity, low cost, and considerable electronic conductivity. Unfortunately, a large volume change during electrochemical processes obstructs its practical application. In this work, a composite of VO nanorings grown on a porous carbon architecture is prepared via a topochemical self-reduction approach. When used as an anode for lithium-ion batteries, improved redox kinetics from enhanced electronic conduction and the corresponding fast lithium-ion diffusion is observed to greatly promote the electrochemical performance of lithium-ion batteries. The resulting composite delivered a reversible capacity of 336 mA h g-1 after 400 cycles at 10 A g-1 with a capacity retention of 85%, owing to the synergistic effect of VO nanorings and porous carbon in alleviating volume changes that result in a long-term cycling ability at a high current density. At 20 A g-1, the composite anode exhibited a rate capability of 235 mA h g-1, superior to all VO-based electrodes reported in the literature. Furthermore, a full cell was first fabricated by employing VO@C-2 as the anode and LiFePO4 as the cathode, which exhibited a capacity of 213 mA h g-1 after 100 cycles at 0.1 A g-1, indicating the potential of VO as an anode for practical application.