富锂锰基正极材料表面改性、结构稳定性及电化学行为的研究

项目名称： 富锂锰基正极材料表面改性、结构稳定性及电化学行为的研究

项目编号： No.51474037

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 矿业工程

项目作者： 习小明

作者单位： 长沙矿冶研究院有限责任公司

项目金额： 90万元

中文摘要： 因充放电过程中结构失稳和表面理化状态差是制约富锂锰基材料电化学性能的关键因素，本项目创新性提出综合利用元素钒（比Mn具有更强M-O结合能）渐变掺杂和高电子-离子混合导电网络层，通过溶胶凝胶-热处理方法一次性地在富锂锰颗粒表面包覆形成钒离子渐变掺杂层和Li3V2(PO4)3/C复合层，改善材料结构稳定性和表面理化特性，提高其电化学性能。研究改性过程对富锂锰基体、包覆层及界面结构的影响，建立制备过程与包覆层形貌、元素分布及界面结构的关系；结合实验研究和理论计算，认识钒离子渐变掺杂层对晶格氧氧化和阳离子迁移的影响规律，揭示其改善材料结构稳定性的微观机制；通过对表面结构和化学态的分析，阐明复合包覆层对材料表面理化特性的影响规律；基于上述研究，建立材料设计-制备过程-结构稳定性/表面理化特性-电化学行为之间的关系，为该类材料在高能量及功率密度、长寿命、低成本锂离子电池技术中的应用奠定基础。

中文关键词： 锂离子电池；富锂锰基正极材料；结构稳定性；表面改性；表面理化特性

英文摘要： As the structural instability and low surface electron-ion conductivity during charging-discharging process are key factors that controls the electrochemical performance of lithium-rich manganese based cathode materials, this project proposes innovatively combining the gradient ions layer of vanadium, which has a stronger M-O bonding energy than manganese, and composite coating layer with high electron-ion mixed conductivity, with the formation of vanadium ion gradient doping layer and Li3V2(PO4)3/C composite layer on the particle surface of the lithium-rich manganese substrate by sol-gel coating and heat treatment process, to improve the material structural stability and surface physicochemical properties, leading the enhanced electrochemical performance. In order to construct the relation between the preparative process, coated layer morphology, element distribution in the coated-layer and interface structure, it is necessary to study the effect of coating and heat treatment process on lithium-rich manganese substrate,coating layer and interface structure. With combination of the experimental results and theoretical computation, this work can understand the microscale mechanism for improving the material structural stability during the charging-discharging process by investigation of effects of vanadium ions gradient doping on the lattice oxygen oxidation and cations transport in the material.Through the analysis of the materials surface structure and physicochemical properties, the relation will be obtained between the surface modification and surface physicochemical properties.Based on the above investigations, the rational relation will be constructed of material design, preparation, structural stability/surface physicochemical property and electrochemical behavior. These fundamental studies are significant for the development of lithium-ion-battery with high energy density, high power density, long life and low cost.

英文关键词： Li-ion battery;Li-rich manganese based cathode material;Structural stability;Surface modification;Surface physicochemical properties