Electrochemical impedance analysis for lithium ion intercalation into graphitized carbons

Electrochemical impedance spectroscopy (EIS) was employed to study electrochemical behviours during intercalation or Li+ into graphitized carbon anode. Analysis was carried out on three regions of frequencies mainly below 0.3 V. The first depressed semicircle in thr high-frequency region had two-dimensional characteristics and did not vary over the entire potential range. The secund semicircle in rbe mid-frequency region had a potential dependency above 0.3 V Impedance spectra. at the lower frequency region were attributed to the finite diffusion of Li+, and the order of the chemical diffusion coefficient was approximately 10(-10) cm(2)/s. (C) 2000 The Electrochemical Society. S0013-4651(99)04-078-1. All rights reserved.