here I have used 3 electrode system, with different types of electrodes such as 6M KOH, 5M NaCl and electrodes are graphene coated Nickel Foams. Is this same potential window can be applied for the CV as well as GCD? I want to know the way how to find out this potential window
for carbon-based EDLC type electrode , you have to use 0 to -1 V in KOH electrolyte, you can use 0 to 0.8 V in NaCl electrolyte. For metal oxide, metal sulfide type pseudocapacitor electrode, you have to use 0 to 0.5 or 0.6 V in KOH. using NaCl for pseudocapacitor electrode will not give a good result. The potential window is normally determined by performing CV until there is the occurrence of HER in negative side and OER in the positive side. HER and OER denote the breakdown of aqueous electrolyte and it will be shown by sharp increase in current density.
for carbon-based EDLC type electrode , you have to use 0 to -1 V in KOH electrolyte, you can use 0 to 0.8 V in NaCl electrolyte. For metal oxide, metal sulfide type pseudocapacitor electrode, you have to use 0 to 0.5 or 0.6 V in KOH. using NaCl for pseudocapacitor electrode will not give a good result. The potential window is normally determined by performing CV until there is the occurrence of HER in negative side and OER in the positive side. HER and OER denote the breakdown of aqueous electrolyte and it will be shown by sharp increase in current density.
Thanks, Dr Dhrubajyoti
And one little question ! When testing asymmetric supercapacitors how they attached the both electrode in CV? did they attach separately to the machine as working electrode or they attached it together? most papers said they used the different type of electrodes as (+) and (-) electrodes and connect those each other for optimisation.
You need to look at the potential gas evolution reactions at either end. If you use sod. chloride, you may evolve chlorine at the anode which is not desirable. Like the previous Researcher suggested do the CV and find out where HER and OER occurs to get an idea of the voltage window
The asymmetric capacitor is like a battery, one electrode is anode and another is cathode. you have to use both anode and cathode together with a separator between them. since the specific capacitance measured by three electrode system is usually more in cathode than that in the anode. Therefore the amount of active material in anode should be more than cathode in the asymmetric setup. Read some articles, you will know how to test asymmetric capacitor
I have another question.
This is regarding the Active material mass of the supercapacitor electrodes. with the composite material some people add carbon powder for enhancing conductivity. When they calculate the CV and GCD graphs, normally they took weight difference in between before and after fabrication.
So the active material mass taken as Composite+ Carbone material?
or Just only Composite material is taken as Active material?
Which one should be correct?
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