for simple capacitors and electrochemical capacitors there is NO difference in capacitance (within 2*SD[1]) values measured from the CV, CD and EIS. Supercapacitors present more complex behavior, each system having specific reasons for possible differences in values measured from the CV, CD and EIS. So,
1) Is it possible, please, to show us capacitance values measured from the CV, CD and EIS for an example of a simple supercapacitor electrode ?
2) In EIS, note, please, the VDC polarization value(s), also.
Generally people go with Cyclic voltammetry (CV) and Charge-discharge (CD) measurements to determine Sp capacitance. EIS is used to determine internal resistance, solution resistance and resistance between active material and the electrode, ie charge transfer resistance.
All the three measurements are different. In CV, we measure current against fixed potential window and scan rate(time). But In the case of charge-discharge, we measure time against fixed potential and current.
My suggestion is record CV for a fixed potential and calculate the average current. Then perform charge-discharge giving specific current what we get from CV curve. This specific capacitance results may be comparable.
The most widely used techniques for electrochemical analysis which measures current vs voltage response of materials at variable potentials. Depending on the experiment, the CV is cycled between initial and final points as it reached its final potential may reverse to its initial point as a results I-E curves obtained in cyclic called cyclic voltammetry.
CV is used to measure the charge storage ability of materials for double layer capacitors and electrochemical energy storage devices. As, from the shape of CV one can conclude whether the processes are reversible or not which occurred on the working electrodes. In addition, the area under the CV curves will be integrated one can get the electrode capacitance.
for simple capacitors and electrochemical capacitors there is NO difference in capacitance (within 2*SD[1]) values measured from the CV, CD and EIS. Supercapacitors present more complex behavior, each system having specific reasons for possible differences in values measured from the CV, CD and EIS. So,
1) Is it possible, please, to show us capacitance values measured from the CV, CD and EIS for an example of a simple supercapacitor electrode ?
2) In EIS, note, please, the VDC polarization value(s), also.
As majorly discussed and point out here by other this is a matter of technique only if there are no mixed capacitive phenomena, but there are an advantage of using EIS as this is a spectrally resolved technique. For more information and technical details on this refer to "Mesoscopic behavior of multi-layered graphene: the meaning of supercapacitance revisited (10.1039/C6CP07775G)." In this paper, the capacitance is obtained either by impedance-derived EIS and CV, but the phenomena was better understood thanks to impedance/capacitance spectroscopically resolved methodology
There are already many good answers from others which I generally agree. In addition, I will use data from relatively slow scan rate in CV (with a good rectangular shape), low current in GCD (with good linearity and negligible iR drop) and low frequency range in EIS (vertical or nearly vertical linear portion on the spectrum) to derive the capacitance values so that kinetic influences can be minimised.
There is nothing in science which is an ultimate best due to human limitations. Some experience researchers have recommended cyclic chronopotentiometry (galvanostatic charge discharge measurement) to be the technique of choice for various reasons. Scientific cumminty is somehow satisfied on these recommendations. Are they best? No. Is it a norm? Yes.
For Reference: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.604.7608&rep=rep1&type=pdf
whenever EIS is measured under VDC value of almost maximum potential value (here 1 V mentioned ), charge transfer resistance is minimised. and we get maximum capacitance value. why?
and why can't we give more potential than maximum operational potential (here I mean more than 1 V)?
remeasuring (2nd time) your capacitance CEIS,1V with the same technique, using the proposal modification of DC-polarization value in EIS (Vdc~1V), showed an almost fivefold (~4.5 *) increase[1] over your initial value of CEIS,0V (Vdc~0V). In other words, the difference among the two common EIS measurements is, o n l y, the value of the polarization (Vdc) parameter.
1. It will be more than fivefold, if you calculate C(1V) using an (equivalent circuit) model technique[2]. So, the new CEIS(1V) will be more close to the higher value of the CCV (270F/g), Cyclic voltammetry (CV) technique.
2. A universal equivalent circuit for carbon-based supercapacitors [Open Access] http://link.springer.com/article/10.1007/s10008-013-2328-4
Fine, so far, for the acquirement of this critical difference, mostly ignored in the related bibliography for the (specific capacitance of) supecapacitors, till today.