钒酸锂基嵌锂负极材料的结构设计、电化学重构机理及性能调控研究

Li3VO4兼具安全性能与能量密度优势，是一种理想的负极材料。然而，其导电性较差，且循环中会出现结构破坏，导致电化学性能不理想。为此，本项目提出利用可控电化学重构，发展具有高嵌锂活性、高导电性二次结构Li3VO4/C的新思路。首先，利用中间液相引碳原位合成方法制备高导电性Li3VO4/C初始结构。液相前驱体有利于碳源、掺杂源的引入及均匀混合，原位碳化可形成C与掺杂Li3VO4在微观尺度均匀复合的Li3VO4/C负极材料，双向增强有望显著提升材料导电性。然后，经恒压、恒流充/放电模式对Li3VO4/C进行电化学活化，系统研究Li3VO4/C在活化过程中的微观结构演变，阐明其电化学重构机理，并经可控电化学重构获得高嵌锂活性与高导电性Li3VO4/C二次结构。最终，系统优化Li3VO4/C电化学性能并获得高性能锂离子电池。项目的实施将为高性能Li3VO4基负极材料的研究与应用提供理论基础与借鉴。

Li3VO4 has been demonstrated to be an ideal anode material for Li-ion batteries owing to its compatible advantages of safe performance and energy density. However, its low electronic conductivity and structure destruction in cycling may lead to unsatisfied electrochemical performance. In this project, we intend to prepare a secondary structure of Li3VO4/C with high lithium insertion activity and high electronic conductivity via controlled electrochemical reconstruction, which provides a new way to obtain high performance Li3VO4/C. Firstly, an initial structure of Li3VO4/C with high electronic conductivity will be prepared via an in situ fabrication method based on introducing carbon source in intermedial solution. The solution precursor is beneficial for the introduction and homogeneous distribution of carbon and doping sources, and the in situ carbonization can lead to the formation of Li3VO4/C with homogeneous hybridization between C and doped Li3VO4 at micro-scale. As a result, the electronic conductivity of the Li3VO4/C can be distinctly improved via double enhancement of electric C and doping. Secondly, the Li3VO4/C will be activated via constant voltage and/or constant current charge/discharge models. After systematically studying the microstructure evolution of the Li3VO4/C in activation, the electrochemical reconstruction mechanism will be clarified, and a secondary structure of Li3VO4/C with high lithium insertion activity and high electronic conductivity will be further obtained via controlled electrochemical reconstruction. Finally, the electrochemical performance of the Li3VO4/C will be systematically optimized, so that high performance Li-ion batteries using Li3VO4/C as anode can be prepared. We propose that the actualization of this project will provide academic foundation and reference for the research and application of Li3VO4 based anode materials for high performance Li-ion batteries.