锂离子电池富锂材料中离子掺杂、表面包覆、表面氧空位修饰的作用机理及其联合机制

The Mechanism of Ion-Doping,Surface Coating,Surface Oxygen Vacancy Modification and Their Joint Mechanism in Lithium-Rich Material for Li-Ion Battery

富锂层状氧化物材料是一种具有类固溶体结构的锂离子电池正极材料,放电比容量可达250 m Ah/g,且价格低廉。因此,富锂层状氧化物材料被认为是最有希望的下一代正极材料之一。然而,富锂层状材料还存在诸多问题,如首次库仑效率低、倍率性能差以及容量和电压平台衰减严重,这些问题阻碍其在商业中的应用。本文从富锂层状材料的晶型结构和首次充放电特性出发,主要介绍了离子掺杂、表面包覆以及表面氧空位修饰的作用机理,并进一步分析了不同掺杂离子和不同包覆材料作用于富锂层状材料后性能差异的原因,以及双掺杂和双包覆的优势。最后,本文针对单纯的离子掺杂、表面包覆、表面氧空位修饰在富锂层状材料改性中的不足,提出了基于上述三种改性方式的联合改性机制,并对该机制进行了简要介绍。

The lithium-rich layered oxide material is a kind of lithium ion battery cathode material,which has a solid solution structure.It exhibits a high reversible specific capacity exceeding 250 m Ah/g,and its price is very cheap.It has been considered as the most promising candidate for the next generation of cathode material.However,the lithium-rich layered oxide cathode material is facing some problems such as high irreversible capacity loss in the first cycle,poor rate capability,as well as serious capacity fading and voltage decay,which hinder its commercial application.In this paper,the structure of lithium-rich layered oxides cathode material and its typical initial charge and discharge curve are introduced,and the mechanism of ion-doping,surface coating,and surface oxygen vacancy modification are mainly focused.Then,the reasons why different doping ions and coating materials applied to lithium-rich layered oxides cathode material have the different effects,and theadvantages of co-doping and double coating are further analyzed.At last,considering the limitations of iondoping,surface coated and surface oxygen vacancy modification during the modification of lithium-rich layered oxide cathode material,the joint mechanisms based on the above three modification methods are proposed,and a brief introduction of this joint mechanism is given.