Self-organized amorphous titania nanotubes with deposited graphene film like a new heterostructured electrode for lithium ion batteries

Abstract

Heterostructures composed of reduced graphene oxide and self-organized titania nanotubes (nt-TiO2) are examined as novel electrode material for lithium-ion batteries. The novelty here resides in the deposition of a graphene-like film on self-organized nanotubes and that, as compared with previous materials, the differences in behavior are significant as the heterostructure combines previously reported advantages of self-organized nt-TiO2 with those emerging from the graphene composites. The preparation of this nt-TiO2/graphene hybrid electrode material is described here. The deposition of a graphene film on self-arranged amorphous nt-TiO2 was confirmed by using SEM, Raman spectroscopy and mapping of composition. Lithium test cells display capacities that can exceed 300 mAh g−1 over 100 cycles and that are therefore superior to those of bare nt-TiO2 and anatase or rutile TiO2–graphene hybrid nanostructures. The excellent rate performance of these electrodes makes charge–discharge possible up to at least 300 C-rate. The impedance spectra show that the graphene-like film improves the interface properties in the hybrid electrode. In addition to the environmentally friendly nature of the active electrode material, the moderate working voltage offers an important safety advantage in that it protects the battery from the electroplating phenomena.