Nitrogen-doped cellulose-derived porous carbon fibers (N-CHPCs) with controllable surface properties and microstructure were prepared to fabricate aqueous supercapacitor with high electrochemical performance at high mass loading of 12.8 mg cm⁻², which may pave a new way to biomass-derived functional carbon materials for advanced aqueous supercapacitors and beyond.

Abstract

Biomass-based porous carbon with renewability and flexible structure tunability is a promising electrode material for supercapacitors. However, there is a huge gap between experimental research and practical applications. How to maintain good electrochemical performance of high mass-loading electrodes and suppress the self-discharge of supercapacitors is a key issue that urgently needs to be addressed. The structure regulation of electrode materials such as heteroatom doping is a promising optimization strategy for high mass-loading electrodes. In this work, nitrogen-doped cellulose-derived porous carbon fibers (N-CHPCs) were prepared by a facile bio-template method using cotton cellulose as raw material and urea as dopant. The prepared N-CHPCs have high specific surface area, excellent hierarchical porous structure, partial graphitization properties and suitable heteroatom content. The assembled high mass-loading (12.8 mg cm⁻²; 245 μm) aqueous supercapacitor has excellent electrochemical performance, i. e., low open-circuit voltage attenuation rate (21.39 mV h⁻¹), high voltage retention rate (78.81 %), high specific capacitance (295.8 F g⁻¹ at 0.1 A g⁻¹), excellent area capacitance (3.79 F cm⁻² at 0.1 A g⁻¹), excellent cycling stability (97.28 % over 20,000 cycles at 1.0 A g⁻¹). The excellent performance of high mass-loading N-CHPCs is of great significance for their practical applications in advanced aqueous supercapacitors.