Kinetics of alkali insertion in single wall carbon nanotubes: an electrochemical impedance spectroscopy study

Electrochemical impedance spectroscopy (EIS) was used to study the kinetics and insertion mechanism of alkali metals in single wall carbon nanotubes ( SWNT). Three distinct processes with very different time constants were ide ntified: charge transfer across the macroscopic electrolyte/electrode inter face, diffusion through the mesoscale porosity of the SWNT electrode, and n anoscale diffusion in individual SWNT ropes. Electrode resistance and capac itance from EIS compare well with direct dc measurements. We propose that a lkalis decorate the internal and external surfaces of the SWNT ropes. (C) 2 000 Elsevier Science B.V. All rights reserved.