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 hours determined by galvanostatic charge/discharge curve measurements. This charge retention was an enhancement of $\sim$350% compared with electrodes without zeolite coating.