Raw carbon nanotubes are synthesized by the electric arc method and pre-doped with lithium. Electrochemical intercalation of lithium into the raw carbon nanotubes pre-doped with lithium is investigated. The results show that the irreversible and reversible capacity of the sample is about 500 and 200 mAh g(-1), respectively. The reversible capacity is higher than that of the raw carbon nanotubes and the open carbon nanotubes. The main reason is that LiNO3 absorbed by the carbon nanotubes is decomposed into LiNO2 at high temperature, and the lithium nitrite can form a film before the electrode contacts the electrolyte. The Li-containing compound film on the electrode surface can prevent the solvent to decompose into other products, so little charge is consumed in the electrolyte decomposition process. Complementary characterization techniques (elemental analysis, X-ray diffraction, scanning electron microscopy, constant-current charge-discharge tests) are used for a full structural characterization of the carbon nanotubes pre-doped with lithium and the electrochemical intercalation of lithium. (C) 2004 Elsevier B.V. All rights reserved.