Effect of Fluorine Substitution on the Electrochemical Property and Structural Stability of a Lithium-Excess Cation Disordered Rock-Salt Cathode  

作　　者：Panpan Li Zhijie Feng Tao Cheng Yingchun Lyu Bingkun Guo 李盼盼;冯志杰;程涛;吕迎春;郭炳焜(Materials Genome Institute,Shanghai University,Shanghai 200444,China)

机构地区：[1]Materials Genome Institute,Shanghai University,Shanghai 200444,China

出　　处：《Chinese Physics Letters》2021年第8期136-143,共8页中国物理快报（英文版）

基　　金：National Natural Science Foundation of China(Grant Nos.51602191 and 52072233);the Beijing National Laboratory for Condensed Matter Physics。

摘　　要：Lithium-excess cation disordered rock-salt materials have received much attention because of their high-capacity as a candidate for cathodes for lithium-ion batteries.The ultra-high specific capacity comes from the coordinated charge compensation of both transition metal and lattice oxygen.However,the oxygen redox at high voltage usually leads to irreversible oxygen release,thereby degrading the structure stability and electrochemical performance.Lithium-excess Li_(1.14)Ni_(0.57+0.5 x)Ti_(0.19-0.5 x)Mo_(0.10O2-x)F_(x)(x=0,0.05,0.10,0.15,and 0.20) with different amounts of fluorine substitution were synthesized.Among them,Li_(1.14)Ni_(0.620)Ti_(0.140)Mo_(0.10)O_(1.85)F_(0.15)exhibits a lower capacity decline,better rate performance,and lower structure damage.The effects of fluorine substitution on the electrochemical property and structural stability were systematic studied by x-ray photoelectron spectroscopy and in situ XRD etc.Results show that fluorine substitution reduces the average valence of the anion,allowing a larger proportion of low-valent redox active transition metals,increasing the transition metal redox capacity,inhibiting irreversible oxygen release and side reaction.Fluorine substitution further improves the structural stability and suppresses lattice deformation of the material.

关 键 词：reaction SUBSTITUTION FLUORINE 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ131.11[化学工程—无机化工]