One-step synthesis of 3D sulfur-doped porous carbon with multilevel pore structure for high-rate supercapacitors

In this work, three-dimensional (3D) interconnected S-doped porous carbon materials are fabricated using bio-waste sodium lignosulfonate as carbon and sulfur precursor by in situ carbonization and subsequent KOH activation process. The as-obtained S-PC-50 has high specific surface area of 1592 m² g^?1, high S weight percentage up to 5.2 wt% and interconnected porous framework consisting of micro-, meso- and macropores. As a result, the S-PC-50 exhibits a high specific capacitance of 320 F g^?1 at 0.2 A g^?1, excellent rate performance with 76.5% capacitance retention after a current density increasing from 2 A g^?1 (200 F g^?1) to 100 A g^?1 (153 F g^?1) and 99% capacitance retention after 10,000 cycles at 5 A g^?1. Besides, the symmetric supercapacitor can deliver a high energy density up to 8.2 Wh kg^?1 at 50 W kg^?1.