A green and simple biomineralization-inspired method to create "net"-like interconnected TiO2 nanoparticles conformably covering reduced graphene oxide (RGO) with high loading density is reported. This method uses polyamine as both the biomineralization agent and linker to manipulate the nucleation, growth, and crystallization of TiO2 nanoparticles on the surface of graphene oxide. The obtained TiO2/RGO composites demonstrate sub-10-nm TiO2 nanoparticles with (001) facets, ultrathin thickness (10-12 nm), and a high surface area of 172 m2 g-1. When used as anode material for lithium ion batteries, the material displayed excellent rate capability and long cycle life; a capacity of 155 mAh g-1 is obtained after 50 cycles at the rate of 5C (1C = 168 mA g-1) and a specific capacity of 115 mAh g-1 is retained after 2000 cycles at the rate of 25C, which is much higher than that of mechanically mixed TiO2/graphene composites. Detailed discharge curve analysis reveals that the high rate and cycle performance are partly a result of the reversible interfacial lithium storage of materials, which might be attributed to the pores in the TiO2 nets on the RGO and may provide a sufficient number of interfaces for accepting both electrons and lithium ions.
Keywords: TiO2; biomineralization strategies; interfacial lithium storage; lithium ion batteries; reduced graphene oxide.