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

Abstract

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 °C exhibits the highest BET surface area of 170 m² 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.