Facile synthesis of Si@TiO2@rGO composite with sandwich-like nanostructure as superior performance anodes for lithium ion batteries

The sandwich-like structural Si@TiO2@rGO composite are prepared via simple sol-gel combined with graphene encapsulation processes and are characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, galvanostatic cycling and electrochemical impedance spectroscopy, in which the stable TiO2 coating can not only prominently restrain volume effect of electrodes but deliver partial capacity for electrodes, and the flexible graphene networks can not only significantly enhance the electronic conductivity but provide extra spaces for volume changes of electrodes. The as-synthetized Si@TiO2@rGO anodes show an initial coulombic efficiency of 76.9%, a charge specific capacity of 1135.1 mAh g(-1) under a test current of 200 mA g(-1) after 100 cycles, a charge specific capacity of 568.1 mAh g(-1) even under a test current of 3000 mA g(-1) and an enhanced diffusion coefficient of lithium ion of 8.008 E-11 cm(2) s(-1) in the 100th cycle, which can be attributed to the synergetic effects of the stable TiO2 coating and flexible graphene networks. Moreover, the Si@TiO2@rGO electrodes still retain integrated sandwich-like structure and uniform element distribution after 100 cycles, which are further revealing their stable physical and excellent electrochemical properties. These noteworthy results exhibit significant potential of the Si@TiO2@rGO composite as anode materials for lithium ion batteries. (C) 2019 Elsevier B.V. All rights reserved.