Sugar‐Derived Carbon‐Based Fiber with Core‐Sheath Structure for Fiber‐Shaped Supercapacitors with High Strength and Superior Capacitive Performance

Abstract Fiber‐shaped supercapacitors are pivotal for wearable device advancement, yet they struggle to achieve both high strength and energy density, hindering their daily practicality in wearable electronic devices. In this study, a sugar‐derived carbon‐based fiber with a core‐sheath structure is designed to enhance the overall performance of fiber supercapacitors. The porous multi‐walled carbon nanotubes (MWCNTs) sheath is bonded by sugar‐derived carbon （SDC）, which effectively prevents aggregation between the MWCNTs, providing a large adsorption surface for the fiber, consequently yielding excellent electrochemical performance, with a specific capacity of 236.7 F cm⁻³. The sugar‐derived core fibers function as the current collector for the fiber electrode, contributing significantly to the mechanical properties (213 MPa). The assembled fiber‐shaped supercapacitors demonstrate outstanding energy density (5.67 mWh cm⁻³ at power density of 45 mW cm⁻³) and flexibility, which can provide stable energy for various electronic devices and has great potential for application in wearable devices.