for specific capacitance of individual electrode measured in 3 electrode config:

C= it/mv, (i=current, t= time of discharge, m= mass of electrode, V= potential difference)

for specific capacitance of individual electrode in symmetric cell measured in 2 electrode config:

C= 2it/mv where m=mass of one electrode, and C= 4it/mv, where m= total mass of two electrode

for specific capacitance of individual electrode in asymmetric cell measured in 2 electrode config:

C= 4it/mv, where m= total mass of two electrode

for specific capacitance of the asymmetric cell or symmetric cell measured in 2 electrode config:

C= it/mv, m= (m1*m2/m1+m2)

Thanks Dr. Dhrubajyoti for your answer 

how about energy density and power density? because some people use 1/2CsqrV and others use 1/8CsqrV for cell, which one is correct?

If you have papers supporting this, kindly provide us.

Thanks to Dr. Dhrubajyoti, for a crystal clear answer.

Yes, The power density and energy density has different values with both the combinations ( symmetric and asymmetric). Sir, Kindly explain that.

for energy density (E) and power density (P) the mail formula is

E= 1/2*CV^2 * (1000/3600) 

P= 3600* E/t 

this formula is valid when the specific capacitance (C) of symmatric or assymatric capacitor cell in 2 electrode system is measured by 

C= it/mv, m= (m1*m2/m1+m2).

if specific capacitance (C) is measured for the electrode in 2 electrode system then multiplication factor of 1/4 have to be used. 

energy density and power density should be calculated for 3 electrode set up, because it is only a half cell, not full cell.

Thank you so much Dr. Dhrubajyoti for your kind help.

I think you mean "energy density and power density should not be calculated for 3 electrode set up" Am I correct?

yes. energy density and power density should not be calculated for 3 electrode set up. these two parameters are used to compare the commercial products, which are full cell.

csp  = 2 *( Qcathode + Q anode)/ m * voltage window 

Dhrubajyoti Bhattacharjya please clear one doubt which I have regarding calculating the energy density; Whether to use cell capacitance or electrode capacitance and in case of asymmetric SC do the two different electrodes have same capacitance values in 2 electrode system as formula suggests (Cs = 4*I*t/m*V)

Dhrubajyoti Bhattacharjya, please share any references for the mass loading formula that you have mentioned above.

for the specific capacitance of the asymmetric cell or symmetric cell measured in 2 electrode config:

C= it/mv, m= (m1*m2/m1+m2).

Thank you.

Dhrubajyoti Bhattacharjya sir, Thank you for your answer.

What will be the formula to calculate the areal capacitance for symmetric supercapacitors?

Thanks in advance.

In a 3-electrode system, electrode capacitance is measured. But in a 2-electrode cell configuration (symmetric or asymmetric), the total cell capacitance makes more sense as it would be next to impossible to create a perfectly balanced device (i.e., an equal contribution from both electrodes) even in the case of pure capacitive current and estimate individual electrode capacitance. Therefore, in a 2-electrode configuration, if you calculate electrode capacitance, it is either under or over-estimated.

It is more appropriate to integrate discharge curves and calculate capacitance. This will eliminate the impact of the non-linearity of curves on capacitance values.

I hope this helps.