Synthesis of size-tunable anatase TiO₂ nanospindles and their assembly into anatase@titanium oxynitride/titanium nitride-graphene nanocomposites for rechargeable lithium ion batteries with high cycling performance.

This paper embarks upon three levels of undertaking ranging from nanomaterials synthesis to assembly and functionalization. First, we have prepared size-tunable anatase TiO(2) nanospindles via a hydrothermal process by using tubular titanates as self-sacrificing precursors. Second, we have densely dispersed the TiO(2) nanospindles onto functional graphene oxides (GO) via a spontaneous self-assembly process. After annealing of the TiO(2)/GO hybrid nanocomposite in an NH(3) gas flow, the TiO(2) surface was effectively nitridated and the GO was reduced to graphene sheets (GS) in order to further fortify the electronic functionality of the nanocomposite. Third, the anatase@oxynitride/titanium nitride-GS (TiO(2)@TiO(x)N(y)/TiN-GS) hybrid nanocomposite was studied as an anode material for lithium-ion batteries (LIBs), showing excellent rate capability and cycling performance compared to the pure TiO(2) nanospindles. Our systematic studies have revealed that the TiO(2)@TiO(x)N(y)/TiN-GS nanocomposites with graphene nanosheets covered with the TiO(2)@TiO(x)N(y)/TiN nanospindles on both sides provide a promising solution to the problems of poor electron transport and severe aggregation of TiO(2) nanoparticles by enhancing both electron transport through the conductive matrix and Li-ion accessibility to the active material from the liquid electrolyte. More generally, the size-tunable TiO(2) nanospindles with their unique (101) outer surface planes provide an archetype for the in depth investigation of their surface-specific and size-dependent physicochemical properties.