High rate capability of TiO2/nitrogen-doped graphene nanocomposite as an anode material for lithium–ion batteries

摘要

TiO2/nitrogen-doped graphene nanocomposite was synthesized by a facile gas/liquid interface reaction. The structure and morphology of the sample were analyzed by X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The results indicate that nitrogen atoms were successfully doped into graphene sheets. The TiO2 nanoparticles (8-13 nm in size) were homogenously anchored on the nitrogen-doped graphene sheets through gas/liquid interface reaction. The as-prepared TiO2/nitrogen-doped graphene nanocomposite shows a better electrochemical performance than the TiO2/graphene nanocomposite and the bare TiO2 nanoparticles. TiO2/nitrogen-doped graphene nanocomposite exhibits excellent cycling stability and shows high capacity of 136 mAh g-1 (at a current density of 1000 mA g-1) after 80 cycles. More importantly, a high reversible capacity of 109 mAh g-1 can still be obtained even at a super high current density of 5000 mA g-1. The superior electrochemical performance is attributed to the good electronic conductivity introduced by the nitrogen-doped graphene sheets and the positive synergistic effect between nitrogen-doped graphene sheets and TiO2 nanoparticles.