Enhanced Electrochemical Properties of Li3VO4 with Controlled Oxygen Vacancies as Li-Ion Battery Anode.

Li₃VO₄, as a promising intercalation-type anode material for lithium-ion batteries, features a desired discharge potential (ca. 0.5-1.0 V vs. Li/Li⁺) and a good theoretical storage capacity (590 mAh g⁻¹ with three Li⁺ inserted). However, the poor electrical conductivity of Li₃VO₄ hinders its practical application. In the present work, various amounts of oxygen vacancies were introduced in Li₃VO₄ through annealing in hydrogen to improve its conductivity. To elucidate the influence of oxygen vacancies on the electrochemical performances of Li₃VO₄, the surface energy of the resulting material was measured with an inverse gas chromatography method. It was found that Li₃VO₄ annealed in pure hydrogen at 400 °C for 15 min exhibited a much higher surface energy (60.7 mJ m⁻²) than pristine Li₃VO₄ (50.6 mJ m⁻²). The increased surface energy would lower the activation energy of phase transformation during the charge-discharge process, leading to improved electrochemical properties. As a result, the oxygen-deficient Li₃VO₄ achieved a significantly improved specific capacity of 495 mAh g⁻¹ at 0.1 Ag⁻¹ (381 mAh g⁻¹ for pristine Li₃VO₄) and retains 165 mAh g⁻¹ when the current density increases to 8 Ag⁻¹. [ABSTRACT FROM AUTHOR]