Facile synthesis and characterization of a SnO 2 -modified LiNi 0.5 Mn 1.5 O 4 high-voltage cathode material with superior electrochemical performance for lithium ion batteries

A thin-layer-SnO modified LiNi Mn O @SnO material 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 LiNi Mn O material 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 Mn ions and the inactive Ni Li O phase in the LiNi Mn O @SnO is less than those in the LiNi Mn O due to incorporation of a very small amount of Sn into the spinel structure upon high-temperature calcination of the precursor. Besides, the mean particle size of the LiNi Mn O @SnO is obviously smaller than that of the LiNi Mn O . The LiNi Mn O @SnO demonstrates much superior electrochemical performance over the LiNi Mn O in 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 , 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 SnO coating layer as well as the structural and morphological modifications of the spinel.