Comparative studies of electrochemical performance and characterization of TiO2/graphene nanocomposites as anode materials for Li-secondary batteries

Abstract

Using graphene oxide (GO) and titanium dioxide (TiO2), various types of composites comprised of graphene-bonded and grafted anatase TiO2 were synthesized without employing a cross-linking reagent in this study. Graphene sheets were uniformly dispersed among the TiO2 particles, to enhance the cyclability and electronic conductivity of the TiO2 anode for lithium ion batteries. A composite of GO prepared with three types of TiO2 (nanoparticles, nanorods, nanofibers) were synthesized by hydrothermal followed by calcination treatment. The reduction of GO increased simultaneously after calcination under argon atmosphere at 400 degrees C for 4 h. To achieve overall better electrochemical performance we used the anatase type of TiO2. The physicochemical properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Surface properties were measured by the Brunauer-Emmett-Teller (BET) Barrett-Joyner-Halenda (BJH) method. The electrochemical properties were also investigated by Galvanostatic charge-discharge and Electrochemical Impedance Spectra (EIS). TiO2 nanoparticles composite with graphene delivered rate capability of 155 mAh g(-1) at 0.5 C and restored the rate capacity of 109 mAh g(-1) after 20 C, with a capacity loss of 30%. TiO2 nanorods composite with graphene benefited from its unique morphology exhibited rate capability of 124 mAh g(-1) at 0.5 C and regain the rate capability of 97 mAh g(-1), with a capacity loss of 22%. In addition, TiO2 nanofibers graphene composite with low surface area 19 m2 g(-1) and pore volume of 0.086 cm(3) g(-1), transported rate capability of 68 mAh g(-1) at 0.5 C and recover the rate capacity of 64 mAh g-1 after 20 C owing to its higher value of lithium-ion diffusion coefficient. (C) 2018 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.