Synthesis of oxygen/nitrogen/sulfur codoped hierarchical porous carbon from enzymatically hydrolyzed lignin for high-performance supercapacitors

Heteroatom codoped porous carbon materials derived from low cost lignin play an important function in the sustainable development of supercapacitors. Herein, enzymatically hydrolyzed lignin (EHL) aminated through Mannich reaction was processed using a facile carbonization activation route to synthesize three-dimensional O/ N/S codoped hierarchical porous carbon (ONS-HPC), in which KOH was the activation agent. The EHL-derived carbon materials possessed high specific surface area, abundant porous structure, and multi-heteroatoms with high doping density. Given the above synergistic effect, the ONS-HPC electrode exhibited a superior specific capacitance of 318 F g-1 at 0.5 A g-1 and excellent rate capability of 62% capacity retention at 50 A g-1. The fabricated asymmetric supercapacitor device based on the ONS-HPC delivered a remarkable energy density of 16.7 W h kg-1 with the power density of 249 W kg-1 and ultralong cycle-lifetime with 99.58% capacitance retention after 10,000 cycles. This result suggests the successful conversion of economical natural lignin to sustainable high-performance porous carbon electrode for supercapacitor via a facile and low-cost synthetic strategy.