Determination of accurate electrode contribution during voltammetry scan of electrochemical capacitors

Abstract

This paper introduces the method which allows determining the accurate electrode contributions during cyclic voltammetry (CV) scan of electrochemical capacitor. As a result of theoretical considerations, a calculation method which reveals voltammetry response of both electrodes during CV of two-electrode cell with reference is developed. The technique is based on the preservation of charge neutrality where the accurate potential sweep rate of individual electrode is dynamically assigned based on its total contribution to the total two-electrode cell voltage ramp. This practice should be used in the research with CV scans of energy storage devices in order to improve their precision. The technique is not an alternative to real three-electrode measurements, where constant sweep rate of working electrode is applied and an oversized auxiliary electrode is used, but it is rather a supplement, which allows observing the true electrode behavior during operation of the capacitor. The paper provides comparison of CV scans obtained with fixed scan rates of both electrodes with dynamic CV scan for electrochemical capacitors operating in aqueous media of 1 mol L −1 Li 2 SO 4 and 7 mol L −1 KSCN. For the first time, the simple procedure is proposed to visualize the real qualitative electrode responses.

A Precursor‐Derived Ultramicroporous Carbon for Printing Iontronic Logic Gates and Super‐Varactors

“…(Figure 4g–i). [ 60 ] It can be clearly seen that the C = f( E ) curve of C meso,E shows a rectangular shape for both blocking and open direction because both cations and anions can easily enter the pores while the asymmetric behavior, typical for the desired CAPode, is mainly determined by C micro,E . As described above, in the open direction both electrodes are working in a similar potential range, while in the blocking direction mainly C micro,E is highly polarized (negatively).…”

“…Using this cyclic voltammetry (CV) data registered in 2electrode setup with RE (Figure S6c, Supporting Information) the C = f(E) curves for the C micro,E and C meso,E (working (WE) and counter (CE) respectively) can be calculated separately according to Slesinski et al (Figure 4g-i). [60] It can be clearly seen that the C = f(E) curve of C meso,E shows a rectangular shape for both blocking and open direction because both cations and anions can easily enter the pores while the asymmetric behavior, typical for the desired CAPode, is mainly determined by C micro,E . As described above, in the open direction both electrodes are working in a similar potential range, while in the blocking direction mainly C micro,E is highly polarized (negatively).…”

Supercapacitor with Carbon/MoS2 Composites

“…Hg/Hg 2 SO 4 served as a reference electrode to monitor performance of both electrodes. The voltammetry response of each electrode was determined according to the previous investigations (Slesinski and Frackowiak, 2018). The specific capacitance per one electrode was calculated according to a very well-known methodology (Laheäär et al, 2015).…”

“…Electrochemical stability of the electrodes working in a symmetrical two-electrode cell with reference was also determined with the use of linear sweep voltammetry (LSV). Voltage of the cell was extended from 0 to ± 1.5 V with a scan rate of 2 mVs −1 with simultaneous monitoring of electrodes potentials (Slesinski and Frackowiak, 2018). It was possible to observe real responses of each electrode since their performance are mutually governed.…”

Recycling Chocolate Aluminum Wrapping Foil as to Create Electrochemical Metal Strip Electrodes

“…This morphology surely increases the electrode surface area which may have led to a higher capacitance observed on the S2 electrode. This has been shown in Table 1 and it is following the C dl for the porous electrode materials as connected by Equation 5 [26]:…”