title: Facile synthesis and characterization of a SnO2-modified LiNi0.5Mn1.5O4high-voltage cathode material with superior electrochemical performance for lithium ion batteries.
abstract: A thin-layer-SnO2modified LiNi0.5Mn1.5O4@SnO2material is synthesized via a facile synthetic approach. It is physically and electrochemically characterized as a high-voltage lithium ion battery cathode and compared to the pristine LiNi0.5Mn1.5O4material prepared under similar conditions. The two materials are proved to be crystals of a well-defined disordered spinel phase with the morphology of aggregates of micron/submicron polyhedral particles. The Mn3+ions and the inactive NixLiyO phase in the LiNi0.5Mn1.5O4@SnO2is less than those in the LiNi0.5Mn1.5O4due to incorporation of a very small amount of Sn2+into the spinel structure upon high-temperature calcination of the precursor. Besides, the mean particle size of the LiNi0.5Mn1.5O4@SnO2is obviously smaller than that of the LiNi0.5Mn1.5O4. The LiNi0.5Mn1.5O4@SnO2demonstrates much superior electrochemical performance over the LiNi0.5Mn1.5O4in terms of specific capacity, rate capability and cyclability. For example, the discharge capacities at current rates of 0.2C, 2C and 20C are 145.4, 139.9 and 112.2 mA h g-1, respectively. A capacity retention rate of ca. 75% is obtained after 500 cycles at 2C rate. The improved electrochemical performance is attributed to the positive effect of the surface protective SnO2coating layer as well as the structural and morphological modifications of the spinel.
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, P. R. China. abyuan@shu.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Ma
authors.forename: Fushan
authors.initials: F
authors.lastname: Geng
authors.forename: Anbao
authors.initials: A
authors.lastname: Yuan
authors.forename: Jiaqiang
authors.initials: J
authors.lastname: Xu