Ionic liquids and SWCNT synergistically construct a dual-transport network in PEDOT: PSS composite fibers for supercapacitor electrodes

A dual-conductive fiber has been engineered with a continuous “ion-electron” network. • The fiber achieves both a capacitance density of 633 F cm −3 and a strength of 247 ± 18.5 MPa. • The fiber supercapacitor shows a high energy density of 41.1 mWh cm −3 . • Supercapacitors have successfully powered a wristwatch, demonstrating their practicality. The rapid development of wearable electronics has created an urgent need for flexible energy storage devices that combine high energy density with fast charging and discharging capabilities. However, the poor intrinsic ionic transport properties of PEDOT: PSS severely limit the efficiency of charge storage and release. To address this critical challenge, this study constructed a highly efficient “ion-electron” dual-continuous synergistic transport network within one-dimensional fibers by regulating the doping concentration of the ionic liquid (EMIM: TFSI, IL) via a simple wet-spinning process. An appropriate amount of IL significantly induces PEDOT chain stretching and orientation, effectively shielding the PSS insulating regions, while preserving the long-lasting conductive network formed by single-walled carbon nanotubes (SWCNT) and the mechanical structure of the fibers. Experimental results demonstrated that the optimized PEDOT: PSS/SWCNT/IL-30 composite fiber achieved a synergistic improvement of record-high volumetric capacitance (633 F cm −3 at a current density of 3 A cm −3 ) and outstanding mechanical strength (247 ± 18.5 MPa). The fiber supercapacitor assembled from this composite fiber exhibited an ultrahigh volumetric energy density of 41.1 mWh cm −3 at a power density of 239.2 mW cm −3 . It retained 78.6% of its capacitance after 10,000 cycles at 7 A cm −3 , revealing excellent rate capability and cycling stability. Furthermore, the fibers woven into flexible fabric devices could power an electronic watch for nearly 50 min, demonstrating superior practical power-supply capability. By clearly elucidating the concentration–structure–property relationship, this study provides key insights and experimental evidence for the design of high-performance, weavable energy storage electrodes, which is of great significance for advancing the practical application of flexible wearable energy storage systems. This paper proposes a structural design strategy for synergistically constructing a dual-continuous “ion-electron” transport network. The fabricated PEDOT:PSS/SWCNT/IL-30 composite fiber achieves an ultra-high specific capacitance of 633 F cm −3 . The assembled symmetric fiber supercapacitor delivers a power density of 239.2 mW cm −3 at an energy density of 41.1 mWh cm −3 . Download: Download high-res image (147KB) Download: Download full-size image