Suppressed self-discharge of an aqueous supercapacitor using Earth-abundant materials

Abstract

Supercapacitors (aka electrostatic double-layer capacitors — EDLCs) offer excellent power storage capacity and kinetics, but suffer under rapid self-discharge. We introduced a zeolite framework into the active capacitor electrode, with the goal to tailor the free desorption energy and thus the self-discharge rate of supercapacitors. Low-cost carbonaceous materials and benchtop production methods were used to create supercapacitor electrodes with a measured specific capacitance of 17.25 F g−1, a coulombic efficiency of 100%, and charge retention of over 25% over 24 h determined by galvanostatic charge/discharge curve measurements. This charge retention was an enhancement of ~350% compared with electrodes without zeolite coating.