A clean process of preparing VO as LIBs anode materials via the reduction of V2O3 powder in a H2 atmosphere: Thermodynamic assessment, isothermal kinetic analysis, and electrochemistry performance evaluation

Abstract

VO is one of the most promising anode materials for lithium ion batteries (LIBs). Herein, we present the clean preparation of VO powder via reduction of V2O3 powder under high-purity H2. Thermodynamic calculation and V–O phase diagram analysis were carried out to ensure reasonable oxygen potential conditions. Isothermal reduction experiments and kinetic analysis using thermogravimetric analysis (TGA) were then performed at 1623 K, 1648 K, and 1673 K under a pure H2 gas flow. The reduction of V2O3 powder appears to obey an unreacted shrinking core model and can be divided into two steps. The first step was controlled by a chemical reaction, the kinetics of which can be described as G(α) = [-ln(1-α)]1/3 with an apparent activation energy of 107.3 kJ·mol−1. The second stage was controlled by gas diffusion, the kinetics of which can be described as G(α) = [1-(1-α)1/3]1/2 with an apparent activation energy of 45.5 kJ·mol−1. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) also were employed for characterizing the morphology of the prepared VO powder. As a result, when the VO was served as the LIBs anode material, the resulting electrodes exhibited a high specific capacity (843 mAh·g−1 after 30 cycles) and remarkable cyclic stability.