Preparation of a TiNb 2 O 7 Microsphere Using Formic Acid and Wrapping with Reduced Graphene Oxide for Anodes in Lithium Ion Batteries

Micron-sized TiNb 2 O 7 (TNO), composed of nano-scaled primary particles, was synthesized using formic acid and a hydrothermal reaction. The TNO microsphere was optimized using formic acid and then wrapped with a graphene oxide (GO) layer using cetyltrimethylammonium bromide (CTAB) surfactants. It was then heat treated in a reducing atmosphere to yield a reduced graphene oxide-wrapped TNO microsphere (rGO-wrapped TNO microsphere) which exhibited superior rate capabilities and cyclability for anode materials in lithium ion batteries. In-depth electrochemical evaluations, including cyclic voltammetry and impedance studies, reveal that both rGO wrapping and the presence of a controlled TNO microsphere improve the electronic conductivity and lithium ion diffusivity of anodes.