Lithium storage in single-walled carbon nanotubes

Here, we investigated the lithium insertion/extraction mechanism in single-walled carbon nanotubes (SWNTs) based both on the empty SWNTs and filled SWNTs, including ferrocene-filled SWNTs (Fc@SWNTs) and C60-filled SWNTs (C60@SWNTs). SWNTs, C60@SWNTs and Fc@SWNTs were systematically investigated as anode materials for Li-ion batteries. The electrochemical performance of the C60@SWNT electrode was slightly better than that of the SWNTs, and the reversible capacity of Fc@SWNTs per unit weight was ∼1.7 times greater than that of the empty SWNTs due to its special tube internal structure. It was proved that the dominant reversible sites for lithium storage in empty SWNTs are the trigonal interstitial channels. Meanwhile, lithium can reversibly insert or extract the inner channels of the tubes after doping with ferrocene; the reversible capacity presented in the inner channels of Fc@SWNTs is about Li1.13C6.