Multifactor Electrical Model

Zone I at low frequency range (1 to 10 mHz) incorporates both series and parallel resistances, where the latter is related to separator leakage current, self discharge, and charge redistribution along the pore length. Of the two resistances, the contribution of parallel resistance is more significant however this could be expected to decrease with extended periods of polarization. 

Zone II (10 mHz to 10 Hz) provides quantitative assessment of the series electronic resistance of the conductors and the ionic electrolyte resistance Rj(T). In this range, the equivalent series resistance is composed of = R + Ri(T) resistances and varies according to the dependence of R, on cell temperature. The ionic resistance is more prevalent at low frequencies as a result of better ion penetration into the pores of the electrode material. 

Zone III shows a predominantly electronic resistance between the frequencies of 10 Hz to 1 kHz attributed to contact resistances of the electrodes, measurement connections, and electrolyte. 

Zone IV depicts inductances present between 1 to 10 kHz resulting from the supercapacitor device and contact wires. 

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