title: Improved Cycling Stability and Fast Charge-Discharge Performance of Cobalt-Free Lithium-Rich Oxides by Magnesium-Doping.
abstract: Layered Li-rich, Co-free, and Mn-based cathode material, Li1.17Ni0.25-xMn0.58MgxO2(0 ≤ x ≤ 0.05), was successfully synthesized by a coprecipitation method. All prepared samples have typical Li-rich layered structure, and Mg has been doped in the Li1.17Ni0.25Mn0.58O2material successfully and homogeneously. The morphology and the grain size of all material are not changed by Mg doping. All materials have a estimated size of about 200 nm with a narrow particle size distribution. The electrochemical property results show that Li1.17Ni0.25-xMn0.58MgxO2(x = 0.01 and 0.02) electrodes exhibit higher rate capability than that of the pristine one. Li1.17Ni0.25-xMn0.58MgxO2(x = 0.02) indicates the largest reversible capacity of 148.3 mAh g-1and best cycling stability (capacity retention of 95.1%) after 100 cycles at 2C charge-discharge rate. Li1.17Ni0.25-xMn0.58MgxO2(x = 0.02) also shows the largest discharge capacity of 149.2 mAh g-1discharged at 1C rate at elevated temperature (55 °C) after 50 cycles. The improved electrochemical performances may be attributed to the decreased polarization, reduced charge transfer resistance, enhanced the reversibility of Li+ion insertion/extraction, and increased lithium ion diffusion coefficient. This promising result gives a new understanding for designing the structure and improving the electrochemical performance of Li-rich cathode materials for the next-generation lithium-ion battery with high rate cycling performance.
authors.affiliation: School of Chemistry and Chemical Engineering, Anhui University of Technology , Maanshan, Anhui 243002, PR China.
authors.forename: Ting-Feng
authors.initials: TF
authors.lastname: Yi
authors.affiliation: School of Chemistry and Chemical Engineering, Anhui University of Technology , Maanshan, Anhui 243002, PR China.
authors.forename: Yan-Mei
authors.initials: YM
authors.lastname: Li
authors.affiliation: School of Chemistry and Chemical Engineering, Anhui University of Technology , Maanshan, Anhui 243002, PR China.
authors.forename: Shuang-Yuan
authors.initials: SY
authors.lastname: Yang
authors.affiliation: School of Chemistry and Chemical Engineering, Anhui University of Technology , Maanshan, Anhui 243002, PR China.
authors.forename: Yan-Rong
authors.initials: YR
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University , Harbin 150080, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xie
keywords: Co-free, Li-rich cathodes; Li-ion battery; cycling performance; density functional theory; fast charge−discharge property; magnesium doping