标题：In SituProbing and Synthetic Control of Cationic Ordering in Ni-rich Layered OxideCathodes
作者：Jianqing Zhao, WeiZhang, Ashfia Huq, Scott T. Misture, Boliang Zhang, Shengmin Guo, Lijun Wu,Yimei Zhu, Zonghai Chen, Khalil Amine, Feng Pan, Jianming Bai,* and Feng Wang*
Ni-richlayered oxides (LiNi1-xMxO2; M=Co, Mn, …) are appealing alternatives to conventionalLiCoO2 as cathodes in Li-ion batteries for automobile and other large-scaleapplications due to their high theoretical capacity and low cost.However, preparing stoichiometric LiNi1-xMxO2with ordered layer structure and high reversible capacity, has proven difficultdue to Ni2+/Li+ cation mixing in octahedral sites.Herein, we report on in-situ studiesof synthesis reactions and the associated structural ordering in preparingLiNiO2 and the Co-substituted variant, LiNi0.8Co0.2O2,thereby gaining insights into synthetic control of the structure andelectrochemical properties of Ni-rich layered oxides. Results from this studyindicate a direct transformation of the intermediate from the rock saltstructure into hexagonal phase, and during the process, Co substitutionfacilities the nucleation of a Co-rich layered phase at low temperatures andsubsequent growth and stabilization of solid solution Li(Ni, Co)O2upon heat treatment in a highly oxidation environment. Optimal conditions wereidentified from the in-situ studiesand utilized in obtaining stoichiometric LiNi0.8Co0.2O2that exhibits high capacity (around 200 mAh/g) with excellent retention. Thefindings shed light on designing Ni-rich layered oxide cathodes with enhancedelectrochemical properties through synthetic control of the structural orderingin the materials.