Free-standing hybrid films comprising of ultra-dispersed titania nanocrystals and hierarchical conductive network for excellent high rate performance of lithium storage

The construction of advanced electrode materials is key to the field of energy storage. Herein, a free-standing anatase titania (TiO₂) nanocrystal/carbon nanotube (CNT) film is reported using a simple and scalable sol-gel method, followed by calcination. This unique free-standing film comprises ultra-small TiO₂ nanocrystals (~ 5.9 nm) and super-aligned CNTs, with ultra-dispersed TiO₂ nanocrystals on the surfaces of the CNTs. On the one hand, these TiO₂ nanocrystals can significantly decrease the diffusion distance of the charges and on the other hand, the cross-linked CNTs can act as a three-dimensional (3D) conductive network, allowing the fast transport of electrons. In addition, the film is free-standing, without requiring electrode fabrication and additional conductive agents and binders. Owing to these above synergistic effects, the film is directly used as an anode in Li-ion batteries, and delivers a high discharge capacity of ~ 105 mAh·g^-1 at high rate of 60 C (1 C = 170 mA·g^-1) and excellent cycling performance over 2,500 cycles at 30 C. These results indicate that the free-standing anatase TiO₂ nanocrystal/CNT film affords a superior performance among the various TiO₂ materials and can be a promising anode material for fast-charging Li-ion batteries. Moreover, the TiO₂/CNT film exhibits an areal capacity of up to 2.4 mAh·cm^-2, confirming the possibility of its practical use.