Revisiting cyclic voltammetry and electrochemical impedance spectroscopy analysis for capacitance measurements

Abstract

The electric properties of an electrode can be evaluated by the determination of the capacitance.However, the literature reports a large panel of experimental protocols for capacitance determination, which involve either cyclic voltammetry (CV) or electrochemical impedance spectroscopy (EIS). Indeed, substantial discrepancies in the assumptions are made between both techniques as in CV, the system is usually considered as ideal (and the current-scan rate relationship is assumed to remain linear at all frequencies), whereas in EIS, the system is usually considered as non-ideal and a CPE element is introduced. In this work, the electric properties of two electrode configurations, namely an Au blocking electrode and an Al electrode with a thin oxide film were investigated using EIS and CV. The capacitive domain was determined for both systems assuming the presence of an ideal and non-ideal system. The results collected from CV revealed a limited linearity between the current and scan rate for both electrode configurations. Finally, a CPE element was introduced to determine the capacitance from CV data and compared to EIS results.

Nanotube‐Boramidic Acid Derivative for Dopamine Sensing

“…The semicircle portion observed at high frequencies expresses electron transferability, while the linear portion at low frequencies represents diffusion. Load transfer resistance (R ct ), which controls the electron transfer kinetics of the redox probe in the electrode interface, is determined by measuring the semicircular diameter [32–34] …”

“…Load transfer resistance (R ct ), which controls the electron transfer kinetics of the redox probe in the electrode interface, is determined by measuring the semicircular diameter. [32][33][34] The Nyquist plots of the bare GC, MWCNTs-NH 2 /GC, and MWCNTs-NH-B(OH) 2 /GC electrodes in 0.2 M KCl solution containing 5 mM [Fe(CN) 6 ] 3À /4À were given in Figure 7. EIS measurements were examined in the frequency range of 100000 to 0.1 Hz at the potential of 0.25 V. The electrochemical impedance spectra of the bare GC, MWCNTs-NH 2 /GC, and MWCNTs-NH-B(OH) 2 /GC electrodes were fitted with Randle's circuit.…”

Simple circuit equivalents for the constant phase element

“…A goal is often to translate the non-ideal CPE element into an equivalent capacitor, notable examples being the Brug equation [32], the oxide layer model [33], and the approaches of [34][35][36]. The interpretation is often limited to specific systems, where the Brug equation is the most widely applied.…”

Modelling of heterogeneous ion transport in conducting polymer supercapacitors

“…Equivalent circuit fitting is a widely adopted method for analysing the processes within SCs, thus it is of interest to compare this method to our developed modelling approach. In equivalent circuit modelling, the non-ideal behaviour of SCs and batteries (given that both have mixed diffusion and kinetics limitations) is often represented by constant phase elements [43][44][45] , whose resultant capacitance is time-scale (or frequency) dependent. Several different equivalent circuits were evaluated for fitting of the generated EIS spectra.…”