Poly(3,4-ethylenedioxythiophene) nanotubes as electrode materials for a high-poweredsupercapacitor

Abstract

We report the fast charging/discharging capability of poly(3,4-ethylenedioxythiophene)(PEDOT) nanotubes during the redox process and their potential applicationto a high-powered supercapacitor. PEDOT nanotubes were electrochemicallysynthesized in a porous alumina membrane, and their structures were characterizedusing electron microscopes. Cyclic voltammetry was used to characterize thespecific capacitance of the PEDOT nanotubes at various scan rates. A type Isupercapacitor (two symmetric electrodes) based on PEDOT nanotube electrodeswas fabricated, and its energy density and power density were evaluated bygalvanostatic charge/discharge cycles at various current densities. We show thatthe PEDOT-nanotube-based supercapacitor can achieve a high power density of25 kW kg−1 while maintaining80% energy density (5.6 W h kg−1). This high power capability is attributed to the fast charge/discharge of nanotubularstructures: hollow nanotubes allow counter-ions to readily penetrate into the polymer andaccess their internal surfaces, while the thin wall provides a short diffusion distance tofacilitate the ion transport. Impedance spectroscopy shows that nanotubes have much lowerdiffusional resistance to charging ions than solid nanowires shielded by an aluminatemplate, providing supporting information for the high charging/discharging efficiency ofnanotubular structures.