Three-dimensional nitrogen-doped hierarchical porous carbon derived from cross-linked lignin derivatives for high performance supercapacitors

Nitrogen-doped hierarchical porous carbons are prepared by hydrothermal crosslinking reaction and KOH activation using sodium lignosulfonate as carbon precursor, 1,6-hexanediamine as crosslinking agent and nitrogen source. As-prepared nitrogen-doped hierarchical porous carbon possesses a high specific surface area (1867.4 m(2) g(-1)), moderate nitrogen-doped content (3.6 at.%) and presents a superior three-dimensional hierarchical porous structure with rich micropores, favorable mesopores and interconnected macropores. The nitrogen-doped hierarchical porous carbon electrode performs high specific capacitance (440 F g(-1) at 0.5 A g(-1)) and excellent cycle stability (94.8% of its initial capacitance after 3000 cycles at 20 A g(-1)) in a three-electrode workstation using 6M KOH electrolyte, while it shows a superior rate capability (80.4% from 331 F g(-1) at 1 A g(-1) to 266 F g(-1) at 20 A g(-1)) in 1 MH2SO4. Furthermore, the nitrogen-doped hierarchical porous carbon assembled supercapacitor delivers a high specific capacitance (370 F g(-1) at 0.5 A g(-1)) and remarkable energy density (18.5 Wh kg(-1) at a power density of 300 W kg(-1), 10.4 Wh kg(-1) at high power density of 12 kW kg(-1)) in 6M KOH electrolyte. The as-prepared nitrogen-doped hierarchical porous carbon with outstanding electrochemical performance is promising for applications in sustainable energy-storage devices. (C) 2018 Elsevier Ltd. All rights reserved.