Three-electrode button cell for EIS investigation of graphite electrode

Electrochemical impedance spectroscopy (EIS) has been used to study the gra phite composite electrode/electrolyte interface in a newly designed three-e lectrode button-type cell. In order to follow the formation of the passivat ion film on graphite, several spectra have been plotted during the first re duction of the electrochemical system. Typical impedance spectra exhibit a high-frequency (HF) impedance loop, which does not evolve much over the sca nned potential range. A middle-frequency (MF) loop appears as the cathodic polarization of the carbon electrode increases, whose characteristics are p otential dependent. In the lower frequency (LF) region, a near vertical str aight line is observed. The attributions of each frequency region are discussed in the present pape r. (C) 2001 Elsevier Science B.V. All rights reserved.