Boosting Capacity Performance of Bio-Waste Lignin-Derived Hierarchical Porous Carbon with Self-Doped Oxygen-Heteroatoms

Herein, oxygen-doped hierarchical porous carbon (OHPC) is successfully fabricated derived from industrial-waste lignin. The as-obtained OHPC is endowed with not only high specific surface area and favorable pore size distribution for accessible ion diffusion and surface charge storage, but also high surface oxygen content (10.78%) for redox pseudocapacitance contributions. With these multiple advantages, the OHCP electrode demonstrates a high specific capacitance of 258 F g−1 at 0.5 A g−1 based on a three-electrode configuration, with a calculated pseudocapacitance contribution up to 19%. Furthermore, the assembled symmetric supercapacitor with OHPC also delivers an extremely superior electrochemical performance with outstanding rate capability, impressive cyclic stability (97.5% capacitance retention over 10,000 times under 2 A g−1), and a high energy density of 9.27 Wh kg−1 at 25 W kg−1. This work provides fresh insights into the high-value utilization of bio-waste lignin and promises great potential in the development of high-performance electrode materials for energy storage.