Specific capacitance of supercapacitor should not depend on scan rate. But it changes with scan rate practically. Specific capacitance increases with the decrease of scan rate as we all know. But, Battery characteristics are significant at relatively lower scan rates (for ex. 0.05 mV/s). In maximum research articles, authors generally use 5 or 2 mV/s as scan rate for maximum supercapacitive behavior.
So, what reasonable scan rate should be used whether reporting maximum specific capacitance for supercapacitors?
The same confusion arises for charge-discharge plot as well. At lower current density, electrode material gives maximum energy density which suits battery behavior. And respectively higher current density, electrode material gives less energy density but higher power density, suits supercapacitor behavior. Like the previous discussion, here the parameter is current density instead of scan rate.
So, my question is again the same, what reasonable current density should be used whether reporting maximum specific capacitance/energy density for supercapacitors? And physical interpretation?
Dear Pandit,
both of these factor will vary with materials type as in case of pure carbons there is no battery type behavior even at lower scan rate/current density but in case of metals it will be very obvious. The current density should close to 1C.
If you go very less scan rate, mobility of ions between electrode and electrolyte will be very proper and you may get very good response.
Dear Nasir,
Yes, I'm concerning about metal oxide electrode for supercapacitor application.
any reference paper that can help me in this topic, plz suggest.
Dear Pandit,
Please see my publication list you will find papers on MnO2 and cobalt and nickel hydroxides. hopefully that will help you.
Dear Selva,
but what reasonable scan rate should be used whether reporting maximum specific capacitance for supercapacitors?
Dear Pandit,
obviously at low rates you will get maximum capacitance but to balance the energy and power density the material should be tested near to their theoretical values that will give you the center position in Ragon Plot.
Dear Mahmood,
Its hard to find theoretical values as different researchers analyse their results for different aspects. Its hard to find universal.
hello Debarati roy chowdhury
When scan rate is very low, redox behavior will be included. batteries are generally worked in low scan rates (0.1 mV/s). All the electrochemical behaviors are analysed in low scan rates. And supercapacitor is associated with fast charge-discharge cycles and fast scan rate only.
https://www.gamry.com/application-notes/battery-research/testing-electrochemical-capacitors-cyclic-voltammetry-leakage-current/
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