An investigation of lithium intercalation into the carbon nanotubes by a.c. impedance

The closed and open carbon nanotube electrodes have been studied as a function of frequency and the open circuit cell potential. A comparison of these spectra reveals different behaviors depending on the form of the carbon nanotubes: for the closed carbon nanotubes the impedance spectra consists of only one arc in the high frequency, for the open carbon nanotubes the impedance spectra consists of two separated semicircles in the high frequency. Analysis based on plausible equivalent circuit models for the carbon nanotubes lead to evaluation the kinetic parameters for the various physicochemical processes occurring at the electrode/electrolyte interface.