Ragone Plots for Electrochemical Double-Layer Capacitors

The Ragone plot (RP) compares devices in energy and power density characteristics, helping engineers decide on a specific energy storage system for technological applications. RP would contrast the performance of several technologies together under similar boundary conditions. Unfortunately, that is not what is happening for electrochemical double-layer capacitors (EDLCs) because conditions for calculating energy and power are not standardized in the literature, resulting in severe discrepancies in the obtained values. With this widespread misconception, RP may become an unreliable tool for characterizing EDLCs. An intervention in this vital issue now becomes necessary. To put action on that, a rational strategy for dealing with measurements needed for EDLCs and calculations to prepare a reliable RP is reported here. This manuscript presents a step-by-step procedure to provide a correct RP. Also, simple theoretical demonstrations of how to get each fundamental equation are presented. In general, this work contributes as a guide to obtain reliable RPs for EDLCs.

Automated summary

The Ragone plot is used to compare energy and power density characteristics, but for electrochemical double-layer capacitors, inconsistencies in calculation conditions lead to unreliable results. A strategy for dealing with EDLCs measurements and calculations, along with a step-by-step procedure for obtaining a correct RP, is presented to help achieve reliable RPs.