Enhancing the performance of Li3VO4 by combining nanotechnology and surface carbon coating for lithium ion batteries

Abstract

With a large capacity and low voltage, Li₃VO₄ has recently attracted much attention as a new insertion-type anode material for lithium-ion batteries. However, the poor electronic conductivity of Li₃VO₄ leads to a large amount of inactive conduct agents in the electrode, which definitely sacrifice the electrode capacity and limit the rate performance. In this work, we propose a strategy in which Li₃VO₄ is first broken into nanometer scale particles by high energy ball milling to increase the active surface and shorten the Li⁺ diffusion distance, and then the particle surface was homogeneously coated with nanolayered carbon via a chemical vapor deposition (CVD) method for electronic conductivity enhancement. The obtained nanosized Li₃VO₄ is uniformly coated by ∼5 nm carbon layers. Compared to the untreated counterpart, the modified Li₃VO₄, dued to the synergetic effects of the nanometer scale and the carbon coating, exhibits an increased first Coulombic efficiency from 68.8% to 79.5%, a higher reversible capacity from 225 to 315 mA h g⁻¹ and a superior rate performance. Importantly, the carbon-coated nanosized Li₃VO₄ with only 5% conductive additive exhibits better performances than the microsized raw Li₃VO₄ with 10% conductive additive, showing the important effects of particle size and electronic conductivity on the electrochemical properties of Li₃VO₄.