How to measure and report the capacity of electrochemical double layers, supercapacitors, and their electrode materials

Abstract

Relevant fundamentals of the electrochemical double layer and supercapacitors utilizing the interfacial capacitance as well as superficial redox processes at the electrode/solution interface are briefly reviewed. Experimental methods for the determination of the capacity of electrochemical double layers, of charge storage electrode materials for supercapacitors, and of supercapacitors are discussed and compared. Intrinsic limitations and pitfalls are indicated; popular errors, misconceptions, and mistakes are evaluated. The suitability of available methods is discussed, and practical recommendations are provided.

Portable and Highly Versatile Impedance Meter for Very Low Frequency Measurements

“…This is however true also in other fields. EIS is also used for the characterization of the electrochemical behavior of energy storage devices and electrode materials for supercapacitors, batteries and fuel cells [25][26][27][28]. As in the case of medical and biological applications, also in these applications the elements to be characterized are modeled by means of multi-element models.…”

Validation of Low-Cost Impedance Analyzer via Nitrate Detection

“…As the double-layer capacitance is dominant at lower frequencies, it can be considered the primary source of the offset error. The error is likely due to differences in the measured double-layer capacitance caused by differences in the applied voltages between the two devices [ 31 , 32 ]. The measured applied voltage on the low-cost device is 11.15% higher than the specified amplitude of 100 mV from Table 2 .…”

Intrinsically conducting polymers and their combinations with redox-active molecules for rechargeable battery electrodes: an update

“…Energy storage with respect to a single electrode does not make sense, it is impossible. Why and how it is frequently reported nevertheless has been discussed elsewhere (Ge et al 2020(Ge et al , 2021Holze and Wu 2021). Storage capabilities in terms of theoretical and/or theoretical gravimetric or volumetric charge densities (sometimes slightly imprecisely called capacities (see Dubal et al 2015Dubal et al , 2016a, in units of A•s•g −1 ) can be calculated.…”

“…In any case in the present report storage data are not provided. Although the dominant aim of many reported studies seems to be a value as high as possible incomplete reporting of experimental parameters and frequently lack of comparability as discussed elsewhere (Ge et al 2020) leave such numbers with rather limited practical value.…”