Impedance of Highly Dispersed Carbon Electrodes

It is known that the impedance technique is one of the most informative electrochemical methods for studying electrodes and electrochemical systems in general. However, as ECSCs are used in a very wide range of characteristic discharge and charging 

An equivalent electric circuit in such a pore was modeled by a transmission RC circuit containing similar resistances of electrolyte within a pore with branching electric capacitances C of EDL of similar values within a pore (Fig. 27.1 lb). At high frequencies, the phase angle is 45° and the intercept at the Z axis is equal to solution resistance outside the pore. At the frequency of - 0, extrapolation of the dependence to the Z axis yields the sum of ionic resistance inside the pore structure and outer serial resistance. 

However, the impedance complex plane plots measured in practice for real electrodes based on HDCMs differ from an ideal complex plane plot suggested by de Levie (1967). Firstly, the slope of a quasidirect line differs considerably from 45° and, secondly, a complex plane plot often contains an approximate semicircle (see Fig. 27.12). 

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