▎ 摘　　要

Sandwich-structured graphene sheets@LiNi0.5Mn1.5O4@graphene sheets (GNRs@LNMO@GNRs) composites have been synthesized by growing graphene sheets(GNRs) on the surface of LiNi0.5Mn1.5O4 (LNMO) via an in-situ method of graphitizing organic compounds. The microstructure, surface morphology and electrochemical performances of GNRs@LNMO@GNRs composites have been examined by X-ray diffraction(XRD), transmission electron microscope(TEM) and different electrochemical tests. The TEM results show that the LNMO nanoparticles are homogeneously dispersed and attached on the GNRs surface. Electrochemical tests demonstrate that the GNRs@LNMO@GNRs electrode exhibits higher discharge capacity, higher coulombic efficiency, better cycling performance and rate capability than the pristine LNMO electrode. These findings reveal that distributing LNMO nanoparticles uniformly on the GNRs might not only provide a plenty of accessible active sites for the fast diffusion of lithium ions, decrease the electrochemical reaction resistance and improve the electronic conductivity, but also suppress the volume changes associated with lithium ion insertion and extraction processes, which result in the improved electrochemical performance of the GNRs@LNMO@GNRs. This study offers an effective way to obtain LNMO cathode materials of lithium ion batteries with high rate performance. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.