Partial surface phase transformation of Li₃VO₄ that enables superior rate performance and fast lithium-ion storage

Abstract

Li₃VO₄ is a promising electrode material for next-generation lithium-ion batteries (LIBs) due to its excellent specific capacity (592 mAh g⁻¹), suitable discharge voltage (0.5–1.0 V), and moderate volume change upon charge/discharge, while it still suffers from low electronic conductivity that usually gives a poor rate capability, low initial coulombic efficiency, and large polarization, imposing a challenge on its practical applications. In this work, a partial surface phase transformation of Li₃VO₄ was initiated via a freeze-drying method followed by a heat treatment in inert gas. Using this method, Li₃VO₄ was integrated with a conductive layer LiVO₂ and carbon matrix. The synergistic effect among Li₃VO₄, LiVO₂ layer, and carbon matrix was systematically studied by optimizing the treatment conditions. When treated at 600 °C in Ar, Li₃VO₄-based composite delivered outstanding electrochemical properties, as expressed by a specific capacity (689 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles), rate performance (i.e., 448 mAh g⁻¹ at 2 A g⁻¹), and longtime cycle stability (523 mAh g⁻¹ after 200 cycles at 0.2 A g⁻¹), which are superior to those without LiVO₂ conductive layer when treated at the same temperature in air. The findings reported in this work may offer novel hints of preparing more advanced anodes and promote the applications of vanadate materials such as Li₃VO₄ for next-generation lithium-ion batteries.