[eng] Theoretical investigations on single-walled carbon nanotubes (SWCNT) have been carried out using ab initio and molecular interaction potential with polarization (MIPp) methodologies to explore the possibilities of Li+ ion insertion through the open-end of nanotubes. Li-nanotube systems can improve the capacity of lithium batteries by using both nanotube exteriors and interiors. Ab initio calculations of the fully optimized nanotubes were used to examine the lithium incorporation in the nanotube through the open-end depending on its diameter size. The favorable interaction of the lithium cation with (5, 0), (6, 0), (7, 0), (8, 0), (9, 0) and (10, 0) zigzag open-ended nanotubes is studied and discussed.