Energy density is  equal to 1/2*C*V2/weight, where C is the capacitance you computed and V should be your nominal voltage (i.e 2.7 V).

Power Density is V2/4/ESR/weight, where ESR is the equivalente series resistance.

You can find a way to compute the above parameters in this Journal paper:

http://www.sciencedirect.com/science/article/pii/S2352152X15000079

SE = (It∆E/m)/2                         

SP = (I∆E/m)/2                          

Where, I is the current in amps used for charge/discharge cycling, t is the time revised discharge, m is the mass in grams of the active material and ∆E is the operating potential window in volt of charge or discharge.

energy density and power density are only should be calculated and compared for a device. This two parameters are generally used for comparison between different energy storage devices such as battery and capacitors. since three electrode system does not represent a capacitor device there is no need to calculate this in this system, 

Capacitance (U)  = time*curent Amps/operating voltage*mass

but in the case of 3 electrode system capacitace= U/4

Energy density= 1/2 C*V2 *1/3.6

Power density = E/∆t *3600

V- operating voltage,

t= time

m- mass

I- Current

I agree with that Energy and power densities are commonly used for two-electrode cells. If you're going to compare your results obtained in the three-electrode cell to the whole super-capacitor device, you should take into account that capacitance of the single electrode will be in 4-fold higher than capacitance of the two-electrode cell in case of the symmetrical super-capacitor (C1~C2) and in 2-fold higher in case of the asymmetrical one where C1>>C2. Resistance also will be different.

Best Regards

For Energy density E=1/2. C*(V)2/3.6

and power density P=E*3600/t (in discharge time)

Hi, may I know why we need to divide 3.6 for energy density and 3600 for power density?

Hello Cheng Kim Sim, Actually that constant comes from the conversion factor. For Energy density, it is needed to divide by 3600( or 1hr) for Wh/g unit. People use F/g directly by dividing just 3.6 instead of 3600 and get Wh/kg. Similarly, for power density Wh/kg to W/kg conversion needs to multiply with 3600 s (or 1hr).

Hi Masud Rana, thanks for the explanation!!!

Hello Murugan Raja, should i take mass of single electrode or both two electrodes in case of symmetric super-capacitors for calculating capacitance. So could you please give some information in this regard.

Hi madam. Normally energy density and power density is calculated in two electrode system when it fabricated as a device. The following formula is used to calculate energy (E) and power density (P),

E = E=1/2. C*(V)^2/3.6 (Wh kg−1)

P = E*3600/t (W kg−1)

Where, ‘E’ is specific energy (Wh kg−1), ‘C’ is the specific capacitance(Fg−1), ‘ V ’ is the potential window (V), ‘P’ is power density (W kg−1) and ‘t’ is the discharge time (s)

The Specific energy density  can be calculated by integrating from 0 to tcutoff (time to reach the cut off potential) the expression V(t)*i*A dt and then dividing for (3600*Mw).In this way you can obtain the specific energy density in Wh kg-1.

[In the expression: i is in A m-2, A is in m2, V in volts, t in seconds and Mw is the molecular weight in Kg]

Graphically, it is the area under the voltage vs. specific capacity curve.

Someone calculate the energy density by multiplying the maximum capacity of the battery for the mid-point potential (Potential of the battery when it is discharged to 50% of its capacity).

For example:

-Maximum capacity delivered by the cell 160mAh g-1= 160Ah kg-1 (respect to the cathode weight)

-Average operating voltage of the cell or mid point voltage e: 3.8V

So finally : 3.8 V×160 mAh g-1=608 Wh kg-1 (respect to the cathode weight)

In this example I simply used the weight of the only positive electrode.

In reality one should include the weight of both electrodes, and the weights of the various components in the cell in reporting the energy density.

I would like to send this paper about your question.

There is a full guide to evaluate supercapacitors devices without misleading.

https://doi.org/10.1002/batt.202100093

If you require any further information, feel free to contact me

Can we write energy density answer in kilo watt per hour per kg

What is of greatest significance in determining classical potential energy differentiation versus force fields' energy [ flux ] is the fact that many of lines of force in a field do something surprisingly retrogressive to the ( non-potential ) energy lying down there .

The current situation of post-modern physics pushes us to be of the belief that interactivity in positions underlying these mentioned lines would not converge to make up the totality of a certain field until and unless the component parts giving rise to such lines are ipso facto spacetime invariancies on the echelon of their counterparts' immanence . But how to arrive at their "Locale"s ?? Can one possibly find out there a unified substance retrospective to the arising of the lines ?

Hello to all of you, is there anyone who can explain in a simple way, if the Energy density of the full cell is 267 Wh/kg, while the Voltage range is 1.7-4.4V, how can I calculate the power density?

Thanks ahead of time.