快离子导体表面修饰Cr掺杂型层状-尖晶石复合固溶体正极材料研究

项目名称： 快离子导体表面修饰Cr掺杂型层状-尖晶石复合固溶体正极材料研究

项目编号： No.51304081

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 矿业工程

项目作者： 刘云建

作者单位： 江苏大学

项目金额： 25万元

中文摘要： 层状-尖晶石复合固溶体正极材料Li0.5+xNi0.25Mn0.75O2+x/2具有容量高，首次库仑效率高，循环性能好等优点，但是较低的电子和离子电导率、较高的阳离子混排及Mn3+含量、循环过程中层状结构的转变等问题限制了该材料的应用。本项目拟采用快离子导体纳米钛酸锂表面修饰结合体相Cr掺杂对其进行综合改性。利用纳米钛酸锂表面修饰并结合核壳掺杂提升表面电导率，Cr掺杂抑制阳离子混排及Mn3+含量并提高体相电导率，利用包覆层和内核中的Ti、Ni、Mn的互掺杂现象提升基体材料电化学性能，通过Ti进入内核表层晶格形成稳定性更好的Li2TiO3成分并结合Cr掺杂抑制Mn3+和阳离子混排，抑制正极材料层状结构的转变。通过本项目研究，揭示钛酸锂包覆和Cr掺杂对锂离子传输特性及电导率的影响规律，Ti、Ni、Mn相互掺杂及层状结构转变的抑制机理，为新型锂离子电池正极材料的开发应用提供新思路和理论。

中文关键词： 层状-尖晶石；富锂材料；体相掺杂；表面修饰；

英文摘要： Layer-spinel composite cathodes Li0.5+xNi0.25Mn0.75O2+x/2 possess high capacity, higher first colomb effiency and better cyclic performance. However, the layered structure transformation, higher cation disorder, low electronic conductivity and lithium diffusivity hinder the practical application of layer-spinel composite cathodes. In this project, nano-size Li4Ti5O12 surface modification combined with Cr doping have been used to improve the electrochemical performance of Li0.5+xNi0.25Mn0.75O2+x/2. Firstly, the conductivity on the material surface can be enhanced with nano-Li4Ti5O12 modificaition and core/shell mutual doped. Secondly, the cation disorder,content of Mn3+ and conductivity of bulk material can be improved with Cr doping. Thirdly, the mutual doping of Ti、Ni、Mn can also improve the electrochemical performance of Li0.5Ni0.25-yMn0.75-yCr2yO2+x/2 and Li4Ti5O12. Moreover, the layered structure transformantion can be restrained by forming steady Li2TiO3 in the surface layer with inleakaged Ti and controlled Mn3+ and cation disorder with doped Cr. This study shows the law and mechanism how the Li4Ti5O12 surface modification and Cr doping influence the lithium ion transport and electronic conductivity, how the Ti、Ni、Mn(Cr) enter into the lattices of core and shell, how the layered structure transformation is

英文关键词： Layer-spinel；Lithium-rich material；Doping；surface modification；