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

Li 3 VO 4 , 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 Li 3 VO 4 hinders its practical application. In the present work, various amounts of oxygen vacancies were introduced in Li 3 VO 4 through annealing in hydrogen to improve its conductivity. To elucidate the influence of oxygen vacancies on the electrochemical performances of Li 3 VO 4 , the surface energy of the resulting material was measured with an inverse gas chromatography method. It was found that Li 3 VO 4 annealed in pure hydrogen at 400 °C for 15 min exhibited a much higher surface energy (60.7 mJ m −2 ) than pristine Li 3 VO 4 (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 Li 3 VO 4 achieved a significantly improved specific capacity of 495 mAh g −1 at 0.1 Ag −1 (381 mAh g −1 for pristine Li 3 VO 4 ) and retains 165 mAh g −1 when the current density increases to 8 Ag −1 .