Ragone Plots for Electrochemical Double‐Layer Capacitors

Abstract

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.

KOH-Activated Hollow ZIF-8 Derived Porous Carbon: Nanoarchitectured Control for Upgraded Capacitive Deionization and Supercapacitor

“…According to SC Ragone plots, both HAC-1 and HAC-3 are located more toward the upper, right region in the plot than MPC and HC, therefore, indicating their superior supercapacitor performance (Figure S7b). 50 On the basis of the result from supercapacitor study, we can envisage superior CDI performances of HACs arising from the synergistic effect of hollow nanoarchitecture and high surface area because CDI also exploits EDL formation on the carbon surface (Figure 5a). Consequently, the CDI performance of the carbon samples were measured in a batch-mode recycling system and the best-performing HAC-1 was further analyzed at varying voltages and cycle numbers (Figure 5).…”

Coconut-husk derived graphene for supercapacitor applications: comparative analysis of polymer gel and aqueous electrolytes

“…16,19 The results displayed that CHG consists of 3-4 layers. 16,19 After the XRD data, the FT-IR data in Fig. S3 (ESI †) also supports the synthesis of reduced graphene since the peaks of the FT-IR spectrum for carbonyl with reduced intensity (1545 cm À1 ), O-H stretching with a broad intensity (3414 cm À1 ), and carbon-oxygen single bond vibration (866 cm À1 ), are in agreement with the XRD and Raman data.…”

Last developments in polymers for wearable energy storage devices

“…Furthermore, parameters as the cycle life, charge/ discharge characteristics, mechanical resistance, durability or degradation against external agents (like water, soaps or ultraviolet radiation) are measured to evaluate the future performance of the energy storage device. 50,70 Currently, there is a lack of high-performance polymeric electrode and electrolyte materials so new studies are emerging. 67,71,72 Polymer composites are very often used in energy storage applications due their high dielectric permittivity and high dielectric breakdown strength.…”

“…Both electric breakdown and dielectric permittivity can be easily measured in a laboratory 68 . Polymer dielectric permittivity 69 can be measured either directly with a DEA machine or by measuring the material capacitance, as shown in Equation (). Last, the power density relation with energy density is shown on Equation (). Furthermore, parameters as the cycle life, charge/discharge characteristics, mechanical resistance, durability or degradation against external agents (like water, soaps or ultraviolet radiation) are measured to evaluate the future performance of the energy storage device 50,70 . Currently, there is a lack of high‐performance polymeric electrode and electrolyte materials so new studies are emerging 67,71,72 …”