Supercapacitors Investigations Part II: Time Constant (EIS characterization) – Supercapacitor – Application Note 34

Abstract

The performances of a supercapacitor are mainly determined by the electrode material. The determination of the supercapacitor characteristics can be performed using many electrochemical techniques. In this note, an EDLC capacitor was characterized using EIS, potential pulse and potentiodynamic investigations. Two equivalent electrical circuit models at low and high frequencies were proposed. The diffusion coefficient of the electrode material was measured. The capacitance, time constant and the equivalent resistant were also determined.

Introduction

To complete the characterization performed on supercapacitor done in the application note #33 [1], it is interesting to know the time constant of supercapacitor. In this note, the time constant of the supercapacitor will be determined by potentiostatic/dynamic and Electrochemical Impedance Spectroscopy (EIS) techniques. Note that in this note (if not indicated):
− the supercapacitor is modeled by a resistor and capacitor in series (Fig. 1).
− supercapacitor is considered as a capacitor and not as a Constant Phase Element [2].

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