Modeling of electric double layer capacitor

Abstract

Electric double layer capacitor (EDLC) is an energy storage device that fills the gap between battery and conventional capacitor. One way to understand EDLC’s charge storage mechanism is through its equivalent circuit analysis. Nonetheless, most of existing equivalent circuits proposed in the past researches are not capable in justifying DC characteristics of the EDLC and hence, prevent the discovery of the technology’s full potential. The project focuses on evaluating electrochemical characteristics of EDLC and proposes a new equivalent circuit model that capable of not only illustrating the charge storage mechanism but also justifying the DC characteristics of the EDLC. Electrochemical impedance spectroscopy (EIS) measurement was carried out on two commercially available EDLCs with the capacitance of 300 and 400 Farad using an electrochemical measuring system. With the aid of EIS Spectrum Analyzer software, the test results were analyzed and a new equivalent circuit was proposed. The impedance spectrum and equivalent circuit model designed from the two samples were compared and their characteristics and electrical behavior were analysed to justify DC characteristics of the samples.