How fractional are super-capacitors? Electrochemical Impedance Spectroscopy (EIS) measurements

Abstract

Super-capacitors are seeing more frequent use in modern electronic designs. Measuring the impedance of such an energy storage device is a good way to characterise how it will behave in real world situations. Therefore this study aims to investigate the present methods of measuring impedance of super-capacitors, with a focus on characterising their properties. There also seems to be an increasing need for better and more cost effective equipment to measure these devices. Many options exist, and some are well suited to the task however most instruments are either too complicated and difficult to use or too expensive (in the 10’s of thousands of dollars) or a combination of both. This work presents a design for such an instrument which can perform these measurements at a fraction of the cost. The functionality and performance are described and compared to current commercial options. Super-capacitors of varying storage sizes and brands are measured and characterised, and discussed in comparison to batteries.