Sol-gel synthesis of nanocrystal-constructed hierarchically porous TiO2 based composites for lithium ion batteries

摘要

Hierarchically porous TiO2 based composites (pure TiO2 and TiO2/carbon (TiO2/C) composite) were synthesized by a facile sol-gel process followed by post- calcination. Poly(vinylpyrrolidone) (PVP) acts as a phase separation inducer as well as a carbon source. The as-prepared TiO2 based composites possess an interesting hierarchically porous structure constructed of cocontinuous macropores and mesoporous skeletons consisting of interconnected nanocrystals and in situ distributed carbon. The hierarchically porous TiO2/C composite shows excellent electrochemical performance with fast lithium ion diffusion and electronic transport, resulting from the hierarchically porous structure and conductive carbon material. The TiO2/C composite calcined at 500 degrees C exhibits the highest BET surface area of 170 m(2) g(-1), superior cycling stability (delivers a remarkable discharge capacity of 132 mA h g(-1) at 1 C after 100 cycles) and excellent rate capability (over 96 mA h g(-1) at 30 C rate). The results indicate that these hierarchically porous TiO2 based composites could be promising anode materials for high performance lithium ion batteries.