Hemicellulose-Derived Carbonaceous Coated-Carbon Cloth as Self-Standing Electrode Materials for a Zinc Ion Capacitor

Conventional binder-containing carbon-based electrode fabrication hinders their performance in aqueous zinc-ion hybrid capacitors (ZICs), creating a demand for alternative sustainable, all-carbon cathodes to overcome limitations in capacity and stability. Herein, we present a simple process for fabricating a free-standing cathode via one-step copyrolysis of hemicellulose, urea, and carbon cloth. During the process, the carbon cloth is simultaneously modified through carbonization, doping, and activation, resulting in porous carbonaceous layers that are welded onto and bridge individual carbon fibers. The strategy establishes an alternative “waste-to-wealth” pathway for sustainable chemistry that aligns biomass valorization with the design of advanced energy storage materials. The obtained CUH electrode exhibits an the specific surface area, introduces abundant defects, and improves electrical conductivity, and delivers a high areal capacitance of 3.8 F cm–2 (397 F g–1) in a three-electrode system. When assembled into an aqueous ZIC, it delivers a high areal capacity of 1.06 mAh cm–2 at 0.5 mA cm–2, alongside good cycling stability and Coulombic efficiency. Impedance spectroscopy tests and morphological analysis under various conditions provide insights into the underlying energy storage mechanisms. This study provides a practical and efficient route to developing binder-free, sustainable carbon cathodes for advanced zinc-ion energy storage devices.