Study On The Synthesis And Modification Of Li_1+x[Ni_0.5Mn_0.5]_1-xO₂（0<x<1） Lithium-rich Cathode Material

The recent development layered lithium-rich Li1+xM1-xO2(M=Ni, Co, Mn,0<x<1)as a new energy materials, which has drawn people’s attention because of it’s highcapacity favorable, good thermal stability and high voltage platform. But forlithium-rich materials exist some problems, such as lower columbic efficiency andbad rate capability, it can’t be widely used in business.In this paper, in order to improve the electrochemical properties of layeredlithium-rich Li1+x[Ni0.5Mn0.5]1-xO2(0<x<1), the cathode materials were prepared viaco-precipitation method. The studying on Li content and sintering temperature tomake sure the best synthesis condition, meanwhile CuO Surface coating and Cobaltdoped was used to makes the material better, the main point as follows:Lithium-rich Li1+x[Ni0.5Mn0.5]1-xO2(0<x<1) were prepared via co-precipitationmethod, and the samples were characterized by kinds of measures, the influences ofsintering temperature and lithium content on structure and electrochemical propertieswere studied. The results showed that when the Li content x is equal to0.13, and thesintering temperature900℃, respectively, the resultant material exhibits a highinitial discharge capacity of218.8mAh/g at a rate of0.1C in the voltage range of2.0~4.6V, and the columbic efficiency is75.7%. Meanwhile, the material exhibitsgood cycling stability with capacity retention of65.2%after100cycles at0.5C.The results show that with proper amount of CuO coating, significant improvementare achieved. At a rate of0.1C in the voltage of2.0~4.6V, the2wt.%-CuO coated sampleexhibits the best electrochemical properties, with a high initial discharge capacity of213.7mAh/g, an excellent columbic efficiency which is above86.9%, and the best cyclingstability with a capacity retention of79.3%after100cycles at0.5C.Lithium-rich Li1.13[Ni0.47Co0.06Mn0.47]0.87O2was prepared by co-precipitationmethod, and this cathode materials exhibits good electrochemical properties,especially rate capability. The result shows that, at a rate of0.1C in the voltage of2.0~4.6V, the initial discharge capacity is231.4mAh/g, and the capacity retention is72.5%after100cycles at0.5C. Meanwhile, the discharge capacity ofLi1.13[Ni0.47Co0.06Mn0.47]0.87O2at0.1C,0.2C,0.5C,1.0C and2.0C are229.6,220.2,200.9,171.3, and123.9mAh/g, respectively.