Facile fabrication of binder-free carbon nanotube–carbon nanocoil hybrid films for anodes of lithium-ion batteries

The electrochemical performance of lithium-ion batteries (LIBs) depends dramatically on the composition, microstructure, and morphology of anode materials. The development of carbon nanotube (CNT)-based anode materials is of great significance. However, the easy agglomeration and winding of CNTs hinder the embedding of lithium ions (Li⁺), leading to the failure of the battery at a high rate when the CNT film is solely used as anode. Herein, binder-free hybrid films of CNTs and carbon nanocoils (CNCs) were fabricated by the facile vacuum-assisted filtration method. The uniform dispersion of helical CNCs in the densely compacted CNTs results in a large number of passways and space to achieve rapid charge transmission. It is found that the storage capacities of Li⁺ are strongly dependent on the mixing ratio of CNTs and CNCs. The highest storage capacities of Li⁺ are obtained in the CNT-CNC film at a mixing ratio of 4:1. The CNT-CNC film electrode still has a charge and discharge capacity of 300 mAh/g even at a high specific current of 800 mA/g, while the CNT film electrode has 150 mAh/g. These results indicate that the CNT-CNC hybrid film is a promising material to be used as binder-free anodes for LIBs.