I wonder how to relate the scan rate to charging rate.
For instance: in an electrochemical process if we used a linear scan voltammetry (LSV) technique that scans voltage from open circuit voltage (2.3–2.7 V) to the terminal voltage (10 mV) at a rate of 0.2 mV/s. We know the total capacity of material is 4200 mAh/g. Then what is corresponding C-rate for above settings?
Any comments or suggestions will be highly appreciated.
@Nadeem
The C rate will vary according to the amount of current passing at any particular moment.
Dave
i did experiments to ev aluate the performance of Iron and nickel electrode for Ni-Fe batteries
see my paper GPKalaignan and KIVasu
a Cyclic voltammetry experiment is a miniature Charge / dis charge experiment
The (Qa/ Qc ratio ) extrapolated to zero sweep rate is used as a criterian
similarly (E p,a / Ep.c) at sweep rates are the measure of reversibilty
it is a charge discharge experiment -
see my papers in JAppl electrochem and Jpoer sources
As Mr. Loveday said, you cannot get the C-Rate out of your information.
The C-Rate corresponds to the flowed charge, which depends besides the given parameters on features like geometry of the electrodes, the cell geometry and side reactions.
Also i do not agree with Prof. Muralidharan that you can calculate the capacity out of a cyclic voltametry besides that you dont do that experiment. The flowing charge depends strongly on the scan rate and also the occuring processes depend on the scan rate. So if you know the correct scan rate window in which no change in the reaction kinetics occur, than you can do an estimation with a CV experiment. But therefor you need to know many details of your sample.
In my opinion, to get comparable answer to the capacity of your sample at a given C-Rate it is mandatory to perform a CCCV Experiment. If you do this for several C-rates, you can extrapolate this by using the Peukert formula to several C-Rates, always assuming that the change in Kinetics is consistent and you dont get any additional side reactions.
Thanks to all for their response. Does that mean that I need to know the active mass of electrode as well?
Yes, you need to know the exact mass. Otherwise you only calculate a charge, not a charge per mass.
maybe the "Randles-Sevcik equation" helps. See also: Zanello, P. - Inorganic chemistry... 2003 (ISBN 0-85404-661-5 or Crouch et al. 2006 - Priciples of instrumental analysis (ISBN 0-49501-201-7)
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