Investigation of supercapacitor cyclic degradation through impedance spectroscopy and Randles circuit model

Abstract High power density and long cyclic stability are important characteristics that make supercapacitor suitable for many industrial applications. Measurement of equivalent series resistance and capacitance, is a general way to investigate performance of the Electric Double Layer Capacitor (EDLC). In this work, a Panasonic EDLC (10F) was investigated under cyclic degradation and monitored using electrochemical impedance spectroscopy (EIS) characterisation and Randles circuit model. After fitting, it was observed that series resistance was increased up to 80% and parallel capacitance was decreased up to 22%. The EIS data were validated using Kramers‐Kronig Transformation to check causality, linearity, and stability in the system.