Fractional-order electric double-layer capacitors with tunable low-frequency impedance phase angle and energy storage capabilities

In this study, we report the electrical response of two sets of solid-state fractional-order electrochemical capacitors for which the low-frequency impedance phase angle can be tuned from -69 degrees to -7 degrees. The configuration makes use of a gel electrolyte in which carbonaceous additives (graphite or reduced graphene oxide) are dispersed at different proportions. Such a disordered electrolyte structure results in subdiffusive charge transport and thus a frequency dispersive capacitive-resistive behavior typical of a constant phase element, which can be useful for both frequency applications and energy storage purposes. Published under license by AIP Publishing.