Ion-liquid based supercapacitors with inner gate diode-like separators

In order to minimize unintentional discharge, supercapacitors are interfaced with a membrane that separates the anode from the cathode—this membrane is called the separator. We focus here on separators, which are structured as electronic diode-like. We call an electrically structured separator “the gate”. Through experiments, it was demonstrated that ionic liquid-filled supercapacitors, which were interfaced with gated separators exhibited a substantial capacitance (C) increase and reduction in the equivalent series resistance (ESR) compared to cells with ordinary separators. These two attributes help to increase the energy, which is stored in a cell, since for a given cell’s voltage, the dissipated energy on the cell, U_R = V²/4(ESR) and the stored energy, U_C = CV²/2, would increase. These were indeed ionic diodes since the order of the diode layout mattered—the diode-like structures exhibited maximum capacitance when their p-side faced the auxiliary electrode.