Facile and fast synthesis of porous TiO2 spheres for use in lithium ion batteries

Abstract Porous anatase TiO 2 spheres have been synthesized by a microwave-assisted hydrothermal reaction of spherical particle precursors followed by annealing in air. The synthesized TiO 2 spheres are formed by interconnected nanocrystals with size of 8.7 nm in average and have grain diameters of 250–400 nm. After annealing at 500 °C, the TiO 2 samples maintain spherical shape and develop highly mesoporous characteristics with a specific surface area of 151 m 2  g −1 . The TiO 2 samples annealed at 750 °C consist of larger aggregated particles with diameters of 500–900 nm and still retain mesoporous anatase structure, but with a reduced specific surface area of 25.6 m 2  g −1 . Electrochemical studies reveal that the porous TiO 2 spheres annealed at 500 °C own very high and stable lithium ion (Li + ) storage capacities of 207, 184, 166, and 119 mA h g −1 at 0.5, 1, 2, and 5 C (850 mA g −1 ) rates, respectively, owing to their highly porous nanostructures and fine spherical morphology. In contrast, the TiO 2 spheres annealed at 700 °C exhibit modest electrochemical performance due to their reduced pore structures and larger crystallite size. The prepared porous TiO 2 spherical particles show great promise for use as high performance anode materials for lithium ion batteries (LIBs).