Energetics of lithium ion adsorption on defective carbon nanotubes

Abstract

We apply the density-functional theory to study energetics of lithium ion adsorption on single-wall carbon nanotubes (SWNTs). We use both the local-density approximation (LDA) and the generalized-gradient approximation (GGA) for the exchange-correlation energy functional. Both the LDA and GGA calculations indicate that adsorption processes of lithium onto the pristine and defective (8,0) SWNT are exothermic with respect to the metallic lithium. On the other hand, the lithium adsorption on the (5,5) SWNT can be endothermic depending on the defect structures. As the defective ring on the surface becomes large, the energy barrier for lithium diffusion through the ring lowers and the peak position of the barrier shifts toward the center of the SWNT. Molecular dynamics simulations are also performed to study the diffusion dynamics of the lithium into the SWNT through the defective rings on the sidewall. These results suggest the possibility of accumulating lithium ions inside the SWNT with large defective rings.