How to calculate the Ragone Plot (energy density&power density) with cyclic voltammetry and galvanostatic discharge-charge. the algorithm is the same with Double Layer Capacitors (EDLCs)， supercapacitors the symmetric cell represents.
For calculating energy density and power density, you have to use the galvanostatic charge-discharge technique, as the power density calculation requires discharge time. You need to use standard formulae for two-electrode capacitance calculation, followed by energy density calculation. Once you know energy density and discharge time from the GCD curve, then you can easily calculate power density. Then you can plot energy density vs power density values calculated at different current densities. Kindly go through the following publications for detailed information:
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You have to conduct galvanostatic charge-discharge measurements of your sample/supercapacitor, then you have to calculate the capacitance values.
Specific Capacitance (Cs)= i x ∆t / m x ∆V
i represents the current in Ampere (A), ∆t is the discharge time in seconds (s), m represents the mass of active electrode material in grams and ∆V is the applied potential window.
Then, the energy density (E), and the power density (P) can be calculated by using the following equations:
E= Cs x (∆V)2 / 2 x 3.6 (for W h kg-1)
P= 3600 x E /∆t (for W kg-1)
Once you get the energy density and power density values at different current densities then you can plot Energy density vs power density to obtain the Ragone plot.
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