Flexible supercapacitors based on a polyaniline nanowire-infilled 10 nm-diameter carbon nanotube porous membrane by in situ electrochemical polymerization

Abstract

The significant volumetric change of electrically conducting polymers (ECPs) during the cyclic charging–discharging process causes the capacitance to decrease and electrodes to degrade. Herein we introduce a new strategy for the synthesis of a flexible supercapacitor device based on conducting polyaniline (PANI) nanowires confined within a 10 nm-diameter multiwall carbon nanotube (MWCNT) porous membrane. The PANI nanowires with a diameter of 8 nm and an aspect ratio over 100 are deposited inside the hollow channels of MWCNTs through an in situ electro-polymerization method. The aligned nanostructure of graphitic CNTs provides both protection to the organic polymers and efficient pathways for charge transfer. More importantly, the confined CNT nano-channels suppress the structural change of the PANI chains during multiple charging–discharging cycles and increase the lifetime of the device. Conducting polymers encapsulated inside MWCNTs as such have significant potential to be manufactured into thin, flexible supercapacitor films. The films we made showed a good electrochemical capacitance of 296 F g⁻¹ at a current density of 1.6 A g⁻¹ and considerable stability with the capacitance loss being less than 5% after 2000 charging–discharging cycles.