Enhanced Lithium Ion Storage Property of Sn Nanoparticles: The Confinement Effect of Few-Walled Carbon Nanotubes

The confinement of Sn nanoparticles inside few-walled carbon nanotubes and its effect on lithium ion storage property have been investigated in detail. It was found that the charge transfer and electronic interaction facilitated Sn to remain in a more reduced state and to link strongly with interior surface of carbon nanotubes by Sn–C bonds, leading to a high reversible capacity of 732 mAh g–1 and capacity retention of 639.7 mAh g–1 after 170 cycles at 50 mA g–1. We also found that the volume restriction inside CNTs protected Sn–C bonds against breakage during lithium insertion/extraction, contributing to the excellent cycling performance with the fade rate of only 0.074% per cycle.