Mesoporous anatase TiO2 submicrospheres embedded in self-assembled three-dimensional reduced graphene oxide networks for enhanced lithium storage

Abstract

A novel composite of mesoporous TiO₂ submicrospheres embedded in three-dimensional (3D) reduced graphene oxide networks (denoted as MTO/3D-GN) as an electrode material for Li-ion batteries (LIBs) was prepared via a facile hydrothermal self-assembly strategy. The as prepared MTO/3D-GN composite shows monolithic 3D interconnected networks of reduced graphene oxide sheets with well-dispersed mesoporous submicrospheres composed of small-size anatase TiO₂ nanocrystals. The novel composite integrates the advantages of mesoporous structure, submicrometer-sized spherical morphology and reduced graphene oxide, thereby providing a high contact area between the electrolyte and electrode, favorable diffusion kinetics for both electrons and lithium ions, and double protection against the volume changes of electroactive TiO₂ materials and excellent electrical conductivity of the overall electrode during electrochemical processes. The evaluation of its electrochemical performance for lithium storage demonstrates that the prepared MTO/3D-GN composite has greatly improved lithium storage properties. In particular, the unique hybrid material has the ability to deliver high reversible capacities with superlative cyclic capacity retention at different current rates for prolonged cycling, and exhibit excellent high-rate performance at a current rate as high as 20 C. The embedded reduced graphene oxide composite with designed mesoporous structure and advanced chemical composition can be used for high-performance LIB negative-electrode materials and other important applications such as solar cells and photocatalysis.