Coaxial wet-spun yarn supercapacitors for high-energy density and safe wearable electronics

TLDR

Yarn supercapacitors promise portable, flexible, and weavable energy storage for wearable electronics, yet their low energy density limits high‑energy applications. The study aims to increase energy density while preserving high power density in yarn supercapacitors. A coaxial wet‑spinning process produces polyelectrolyte‑wrapped graphene/CNT core‑sheath fibers that serve directly as safe electrodes in two‑ply yarn supercapacitors. The resulting yarn supercapacitors achieve ultra‑high capacitances of 269 and 177 mF cm⁻² and energy densities of 5.91 and 3.84 μWh cm⁻², and a cloth supercapacitor interwoven from two 40‑cm coaxial fibers outperforms commercial capacitors, demonstrating scalable, high‑performance wearable energy storage.

Abstract

Yarn supercapacitors have great potential in future portable and wearable electronics because of their tiny volume, flexibility and weavability. However, low-energy density limits their development in the area of wearable high-energy density devices. How to enhance their energy densities while retaining their high-power densities is a critical challenge for yarn supercapacitor development. Here we propose a coaxial wet-spinning assembly approach to continuously spin polyelectrolyte-wrapped graphene/carbon nanotube core-sheath fibres, which are used directly as safe electrodes to assembly two-ply yarn supercapacitors. The yarn supercapacitors using liquid and solid electrolytes show ultra-high capacitances of 269 and 177 mF cm−2 and energy densities of 5.91 and 3.84 μWh cm−2, respectively. A cloth supercapacitor superior to commercial capacitor is further interwoven from two individual 40-cm-long coaxial fibres. The combination of scalable coaxial wet-spinning technology and excellent performance of yarn supercapacitors paves the way to wearable and safe electronics. High-energy yarn supercapacitors are desirable for safe and wearable electronics. Here, Kou et al. use a coaxial wet-spinning assembly method to fabricate core-sheath fibres of polymer-wrapped carbon nanomaterials and demonstrate high-performance supercapacitor applications.