Facile synthesis and characterization of a SnO2-modified LiNi0.5Mn1.5O4 high-voltage cathode material with superior electrochemical performance for lithium ion batteriesElectronic supplementary information (ESI) available: Rate performances, charge/discharge curves at 0.2C rate and typical discharge profiles at different C-rates of LNMO and LNMO@SnO2 with an electrode active material mass loading of ca. 4 mg cm−2 (Fig. S1); O 1s and C 1s XPS spectra of LNMO and LNMO@SnO2 electrodes at the discha

A thin-layer-SnO 2 modified LiNi 0.5 Mn 1.5 O 4 @SnO 2 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 0.5 Mn 1.5 O 4 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 3+ ions and the inactive Ni x Li y O phase in the LiNi 0.5 Mn 1.5 O 4 @SnO 2 is less than those in the LiNi 0.5 Mn 1.5 O 4 due to incorporation of a very small amount of Sn 2+ into the spinel structure upon high-temperature calcination of the precursor. Besides, the mean particle size of the LiNi 0.5 Mn 1.5 O 4 @SnO 2 is obviously smaller than that of the LiNi 0.5 Mn 1.5 O 4 . The LiNi 0.5 Mn 1.5 O 4 @SnO 2 demonstrates much superior electrochemical performance over the LiNi 0.5 Mn 1.5 O 4 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 −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 SnO 2 coating layer as well as the structural and morphological modifications of the spinel. The SnO 2 -modified LiNi 0.5 Mn 1.5 O 4 high-voltage Li-ion cathode material exhibits superior electrochemical performance, and the synthetic method has the advantage of being facile.