Conjugated Microporous Polymer Network Grafted Carbon Nanotube Fibers with Tunable Redox Activity for Efficient Flexible Wearable Energy Storage

Abstract

Fiber-shaped supercapacitors (FSCs) are promising energy storage devices that meet the growing demands for the miniaturization, flexibility, and compatibility of wearable electronics. However, when compared with batteries, the low energy density remains the main limitation to practical applications. A conjugated microporous polymer (CMP) network synthesized using Buchwald–Hartwig cross-coupling reactions featured tailorable porous structures, reversible redox chemistry, and demonstrated highly efficient capacitive performance. Herein, the CMP network that grafted on carbon nanotube fibers (CNF@CMP) with high areal specific capacitance (671.9 mF cm–2 at a current density of 1 mA cm–2) was successfully achieved for a polytriphenylamine (PTPA)-based network. All-solid-state symmetrical-twisted CNF@PTPA FSCs fabricated with PVA/H3PO4 as a gel electrolyte exhibited a high specific areal capacitance of 398 mF cm–2 (0.28 mA cm–2), a maximal operating voltage of 1.4 V, and an energy density of 18.33 μWh cm–2. Moreover, they showed excellent flexibility and mechanical stability retaining 84.5% of the initial capacitance after 10,000 bending cycles. These materials provide a new route to high-performance wearable supercapacitors (HPWS) with wide potential applications in wearable electronics, as shown by the examples provided.