缺陷调控设计、制备高能量高功率LiVPO4F正极材料及其电化学性能研究

Polyanion LiVPO4F has a flat discharge plateau as high as 4.2 V (vs. Li/Li+) and is a novel high capacity, high safety and high thermal stability cathode material for lithium ion batteries. Therefore, it is anticipated as a promising update of current LiFePO4 cathodes for power batteries such as in electric vehicles. The present project uses the "defects creation-partial correction" strategy to design and regulate defects structure in LiVPO4F so as to increase its electron concentration and ion mobility, and ultimately its electrochemical performance. Combining ab-initio computation with experimental study, the relationships of crystal structure with physicochemical properties will be comprehensively investigated, the mechanism of electron and ion transportation will be deeply understood, and the key factors influencing the charge/discharge efficiency, polarization, rate and cycling performance of LiVPO4F are aimed to be clarified. The thermal dynamics and kinetics will be systematically investigated with the purpose of improving the high temperature high rate cycleability and lifetime of power lithium ion batteries. Consequently, the basic theory of developing high performance battery materials by the bottom-up defect regulation method is hopefully to be established, and the commercialization of LiVPO4F cathode will be accelerated

聚阴离子型LiVPO4F是一种放电平台电压高（4.2V vs. Li/Li+）、放电平台电压平、高比电容量、高安全性、高温稳定性的新型锂离子电池阴极材料，是优秀动力型电池阴极材料LiFePO4的升级换代材料。本项目利用"制造缺陷-再部分修复缺陷"的思路引入缺陷设计，通过调控材料结构缺陷来增加LiVPO4F材料的电子浓度和离子迁移率，提高材料的电化学性能。结合材料的第一性原理计算和实验研究，全面、深入分析LiVPO4F材料的晶体结构特别是原子排列与物化性能的关系，探索其中电子传导和离子输运的机制和原理，进而找出影响材料的充放电效率、极化现象、倍率和循环性能的关键因素。系统研究LiVPO4F材料的电极热力学、动力学过程，提高动力型锂离子电池的高温高倍率循环稳定性和服役寿命，建立自下而上缺陷调控法制备先进锂离子电池活性材料的理论基础，促进LiVPO4F材料的产业化。

针对聚阴离子型LiVPO4F电子和离子电导率低的问题，项目通过"制造缺陷-再部分修复缺陷"的思路引入V位缺位设计，再利用部分过渡金属掺杂调控材料结构缺陷来增加LiVPO4F材料的电子浓度和离子迁移率，提高材料的电化学性能。通过大量实验研究，全面、深入分析了LiVPO4F材料的晶体结构与物化性能的关系，探索其中电子传导和离子输运的机制和原理，进而找出影响材料的充放电效率、极化现象、倍率和循环性能的关键因素。利用缺陷调控方法还研究了Li3V2(PO4)3、NaVPO4F材料的结构与性能的关系。