  The mean axial velocity of lithium irons across the entrance of carbon
nanotube VLi is an important factor for the charge-discharge performances of
rechargeable Lithium battery. The molecular dynamics simulation method is
adopted to evaluate the factors and their effects on VLi which include the
diameter of carbon nanotube, functional group type on the port and the number
of a given type of functional group. The statistical analysis of the
calculation results shows that: In the selected carbon nanotubes of four
different diameters, VLi will gradually rise with the increase of CNT diameter
due to lithium irons migration resistance decreasing; as the port of CNT is
successively modified to hydrogen (-H), hydroxyl (-OH), amino (-NH2) and
carboxyl (-COOH), the corresponding migration resistance of lithium ions is
enhanced resulting in the dropping of VLi; in comparison to the effect strength
of four types of functional groups on VLi, -COOH shows strongest, -NH2 and -OH
perform relatively weaker, and the effect difference between -NH2 and -OH is
very small, -H displays weakest; When the number of a given non-hydrogen
functional group on the port sequentially increases, it also shows a trend that
lithium ion migration resistance gradually increases which makes VLi decreases
in turn. The more influential the functional group, the greater the impact of
functional group number changes on VLi. The results of this paper have some
significance on the precise production of lithium-ion battery electrode
materials, enhancing the overall battery cycle efficiency and charging speed.
