Supercapacitor Charge-Discharge Cycling

This simulator runs a real galvanostatic charge-discharge (GCD) test on a model electric double-layer capacitor: a constant current ramps the terminal voltage up until it hits the cell's rated maximum, then reverses to discharge it back to zero, repeating indefinitely. The 3D scene shows why the capacitance exists at all — electrolyte cations and anions physically migrate to the surfaces of the two porous carbon electrodes as voltage builds, forming the nanometre-scale Helmholtz double layer that stores the charge electrostatically rather than through a chemical reaction. Adjust the cycling current, the effective double-layer capacitance and the equivalent series resistance to see how each one reshapes the voltage-time trace, the instantaneous IR drop at current reversal, and the stored energy.