Yes, they should be comparable, particularly if measured at comparable currents. If there are differences, the cause would be likely due to the difference in current. A higher current may give a smaller capacitance value due to kinetics. For measuring capacitance, the two methods are comparable. However, they each can provide different information. For example, CV may tell you if there could be any non-capacitive redox reaction involved, whilst GCD can tell you the resistance of the cell or electrode. 

I always have problems with GCD, when I reduced my current to 0.5A/g, my graph can't seem to charge up or discharge to the required potential and renders the shape of the graph not symmetrical at all. For example my charging time is 200s but discharging time when up to 400s.

The GCD graph's shape with 1A/g is good but I can't get the results of the CV, that's why I want to reduced the gravimetric current.

What was the current on your CV? Any chance you may convert your CV and GCD plots to picture files and upload them to here?

The electrode seems to be taking too much time to discharge. Even with the extra discharging time the specific capacitance calculated is still far from the value obtained from CV

The flat portion on the discharge branch between 0 and -0.1 V is obviously due to redox reactions, likely reduction of proton in the electrolyte, on the electrode. This is also shown on the CV in the same potential range.

what is a CV ? a miniature experiment of charge/ discharge with out complications

i used CV in 1985 to find out the reversiblity of electrodes used  batteries

to me a CV experiment is a charge / discharge study carried out  in a short interval

Coming to Charge/ discharge of the assembled cells -  it is for a long duration  - a completely different assembly

i expect both values should not be the same

you can  believe an regular  Charge/ discharge values

George Zheng Chen  used phrases we normally do not use  -- i am electrochemist for the past 46  years

Prof V.S Muralidharan: You may indicate here what phrases I used that you normally do not use. That will be helpful for the rest of us.  

we use  the term capacity of a battery   for lead acid  batteries  based on current  obtained based on mass of the plate as we use excess active material in Pb batteries(150%)

In the case of Ni-Cd, Ni-Fe we use the term the term Charge/ discharge rates- Crates  like C. C/2/,C/5 and so on

now in the case of Super capacitors charge is stored due to only adsorption  - adsorbed species store charge and no faradic reaction occurs

Though these are known well we still compare with batteries -

In CV the appearance of the peak is due to adsorption  - not due to faradic reaction -hence it is truly irreversible  unlike in batteries

capacitance ( capacity ) goes with the single electrode while specific capacitance is for batteries - but we use for Super capacitor too

the trouble comes as we compare both capacitors and batteries

CV is good to evaluate a single electrode  and for Super capacitors real charge/ discharge studies

please see classical book by Conway/ S.Srinivasan

partially answered

i expect both values should not be the same

you can believe an regular Charge/ discharge values

Yes Prof. V.S. Muralidharan is correct.

CV and charge-discharge is different

In addition CV is a basic characterization and supporting for charge-discharge.

In CV within a fixed time (V/s)  we measure the current. But in the case of practical applications discharging time within a fixed current matters.

the CV capacitance is comparable with  charge discharge  experiment as prof  George Zheng Chen said very clearly. when the average current of CV is comparable to applied constant current in charge discharge experiment. where the slop of charge discharge curve is nearly equal to scan rate in CV . which is applicable to EDLC capacitance. however, pseudo capacitance also give comparable result in whole (average of all points)   

All CV currents are diffusion currents

you should extrapolate to zero sweep rate to compare 

i think it is not needed, if we extrapolate to zero sweep rate which means that the potential is constant or ideally speaking it is  in ocp. than no current  is evolved which leads to capacitance  is zero/constant.

it is not always true saying  All CV currents are diffusion currents and it is mainly depended on potential window.

in some case we find the difficulties in charging and discharging at low current rate as this person (John Kevin Gan ). the irreversible reaction will take place even at low scan rate /current  because at low current/ scan rate  has enough time for this irreversible reaction take place . first correct potential  window must be fixed by CV .

only at sweep rates results can be compared

please SEE for theoretical details  my papers in J POWER SOURCES and J appl electrochem in 1983-1988

i back 46 years  knowledge

can you give correct link  to your paper.  i have one question. is it my explanation is wrong. if it so, please  indicate where i am wrong.

In CV all the currents are diffusion currents

Ep and Ip  are functions of time ; zero sweep rate means  near steady steady state

at the time the current may be free of diffusion 

you can use it

sorry i left India and left electrochem too

i work on sociology and neuro transmitters

contact Mr Gunasekaran librarian CECRI 

www.cecri.res.in

Not all CV currents are diffusion controlled, depending on the relative rates of the diffusion and charge transfer steps. For surface confined processes with both oxidised and reduced species on the electrode surface, no diffusion is be involved. This is often the case for supercapacitor studies.

No

CTR is faster ; measurements are difficult

in CV the currents are all diffusion and adsorptive

psudo capacitance arises due to adsorption- adsorbed charge storage

example super capacitors 

the rectangular we see is due to charge storage

see S.Srinivasan and JOM Bockris work on capaciotrs

for psudo capacitance see the book by E.GILEADI

How do you explain the proportionality of current vs. scan rate, not square root of scan rate?

good question

Fick's law states diffusion  concentration with  square root variation of time

but not a big thing

both are time dependent

adsorption pseudo capacitance follow sweep rate sometimes if the adsorption is time dependent one

in CV as potential is time depandant current becomes one

Adsorption may involve desorption, and is not exactly the same as the supercapacitor electrode. The latter has the redox active materials permanently attached to the electrode as a coating. Particularly in a very thin coating, diffusion is not present for any of the redox active species.

with out diffusion process there is  few  electro chemistry 

even on a film electrolyte has to diffuse

adsorption/ desorption in super capacitors are also known 

Redox species do not diffuse in the thin coating cases. The diffusion of ions of the electrolyte occurs but it is not controlling the charge transfer reactions on the electrode and hence not shown on the CV current.

Good

redox species do undergo CTR

then why current should vary with sweep rate?

Why should current vary with sweep rate?

This is because the total amount of redox active mass is constant on the electrode surface, which means the total amount of charge to be transferred at the explored potential range is also a constant. Therefore, when the sweep rate is low, there is enough time for all the charge to be transferred with the potential range, and low current occurs (roughly, time x current = charge). At a higher sweep rate, the time is short and the current needs to be high to transfer all the charge.

Of course, this proportionality between current and sweep rate is based on the assumption that the charge transfer reaction is sufficiently fast.