Resilient mesoporous TiO2/graphene nanocomposite for high rate performance lithium-ion batteries

Abstract

Mesoporous TiO2/graphene composite is synthesized using graphene oxide (GO) and cheap TiOSO4 as precursors via a facile one-step hydrothermal route. In this process, Ti(OH)4, the hydrolysis product of TiOSO4 in acidic environment reacts with functional groups (epoxy bridges, hydroxyl groups, carboxyl groups) on the GO sheets, which establishes strong Ti-O-C chemical bonds that link in situ formed TiO2 nanoparticles and graphene sheets together. Fourier transform infrared (FT-IR), Raman and X-ray photoelectron spectroscopy (XPS) confirms the existence of the Ti-O-C chemical bond in the resultant composite. Such kind of chemical bond could prevent the aggregation of TiO2 nanoparticles, avoid the restacking of graphene sheets, facilitate the fast transport of the Li-ions, enhance electronic conductivity, offer a high tap density, maintain the structural integrity during charge/discharge process, and consequently achieve excellent cycle stability and high rate capability in Li-ion batteries. At the current density of 5000 mA g-1, the discharge capacity of the composite can be readily retained at 141.7 mAh g-1 after 100 cycles, which is outstanding among the TiO2 composites in the literature.