Probing the capacity loss of Li3VO4 anode upon Li insertion and extraction

Fast progresses have been made for Li3VO4 since it is firstly reported as an anode material in 2013. However, most of current works focus on its performance improvement in capacity, rate and cycle capability, little study has been done to address its charge/discharge mechanism. Herein, we try to give a comprehensive understanding of its charge/discharge behaviours and capacity loss mechanism. By controlling the depth of discharge, it is found that the first irreversible capacity loss is related to the formation of SEI film as well as the structure distortion initiated by first lithiation. And the cycle performance of Li3VO4 can also be influenced by the discharge depth. First principle calculation is also performed to predict the structure changes of Li3VO4 upon different Li insertion amounts, and the results prove that the volume expansion and crystal distortion becomes more irreversibly at deep discharge. Along with cycle number, the accumulated structure deterioration results in the decline of material crystallization and structure orders, leading to capacity loss upon cycles. Based on the systematically analysis, future optimization of Li3VO4 are also proposed, for instance, the interface modification by surface coating or optimization of electrolyte components, and structure stabilization by ion doping. (C) 2017 Elsevier B.V. All rights reserved.