Electrochemical intercalation of lithium into open-end multi-wall carbon nanotubes well-oriented on a copper foil

Well-oriented multi-wall carbon nanotubes (MWNTs) were adopted as an electrode material in lithium ion battery to study the intercalation and de-intercalation effects of the lithium ions for end-opened and end-closed MWNTs. The structures of the two kinds of the oriented MWNTs were estimated by wide angle X-ray diffraction (WXRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The different electrochemical properties were investigated by galvanostatic discharge-charge and cyclic voltammetry experiments in a three-electrode cell under a highly pure argon atmosphere. The results indicate that the electrode of the end-opened MWNTs had better performances than that of the end-closed MWNTs; the inner cores of the end-opened MWNTs were suitable for lithium ion insertion. The coulombic efficiency of the end-opened MWNTs reached 95.8% and the reversible capacity kept 314 mAh.g ^-1 after the first discharge and charge cycle. These values under the further discharge-charge cycles were almost the same, indicating the good repeatability.