The development of high-performance rechargeable lithium-ion batteries (LIBs) using carbon materials as negative electrodes for efficient energy storage devices has become one of the key research topics in today's information-rich mobile society. Various types of carbon materials with different micro/macrostructures have been investigated in order to improve the electrochemical performance of the batteries, owing to the completely different lithium ion charge (lithium insertion) and discharge (lithium extraction) mechanisms for different carbons.

Recently, nanostructured carbon materials received a great deal of attention in battery community due to their short lithium-ion path length, large surface area and extremely charming surface activities so as to improved rate capabilities and cyclic characteristics as the negative electrode materials of LIBs.

We present here one type of relatively novel route to prepare activated carbon nanofibers that rely on the electrospinning technology with subsequent carbonization and physical/chemical activation processes. Activated carbon nanofibers have high surface area and provide fast lithium charge/discharge kinetics. The procedure of preparing active carbon nanofibers includes: i) using polyacrylonitrile (PAN) and Zinc Chloride (ZnCl2) solutions in N, N-dimethylformamide (DMF) to form polymer composite nanofibers through electrospinning; ii) thermally treat these composite nanofibers to obtain carbon composite nanofibers; and iii) chemically activate carbonized nanofibers using hydrochloric acid and hot deionized water. In order to explore their application in LIBs, we used these dimensionally thin, mechanically tough, electrically conductive carbon nanofibers as negative electrodes to fabricate coin cells without adding any other binding or conductive materials. The surface morphology and thermal properties of the PAN/ZnCl2 were characterized using ATR-FTIR spectroscopy, SEM, TEM, and DSC. The results indicate that there exist interactions between PAN and ZnCl2. We also characterized the microstructure and morphology of activated carbon nanofibers through various analytical techniques, such as SEM, TEM and BET, and evaluated their electrochemical performance such as charge/discharge cycling and electrochemical impedance spectra (EIS). Our results demonstrated that, compared with unactivated nanofibers, activated carbon nanofibers have much higher specific surface area and larger pore volume. More importantly, these activated carbon nanofiber electrodes provide stable charge-discharge capacities to the resultant lithium-ion batteries, especially at high current densities.