Lignin-based carbon materials with high mesopore rate for symmetric supercapacitors

This study aimed to develop more environment-friendly supercapacitor (SC) electrode materials with enhanced performance. Herein, an easy and eco-friendly method was devised for the preparation of hierarchical porous lignin-based carbon materials (LBCMs). During the preparation process, air as an activator favored the formation of mesopore-dominated structures, whereas, static air acted as a protective agent for the carbon skeleton. Additionally, the hierarchical porous structure and electrochemical performance of LBCMs were regulated by changing the reaction temperature and time. The optimized LBCM-800-1 showed a large specific surface area (1471.27 m2 g-1) and mesopore rate of 71.58 %. As an SC electrode material, the three-electrode system showed a high specific capacitance of 194.2 F g -1 at 0.5 A g -1 in 6 M KOH and a multiplicative performance of 88.64 % at 5 A g-1. Symmetric SC based on LBCM-800-1 exhibits an energy density of 10.4 Wh kg-1 at a power density of 250 W kg-1 and a 100 % cycle retention rate after 10,000 cycles of charging/discharging. The sustainability of the precursor, the simple and environmentally benign preparation process, and the excellent electrochemical performance of LBCM-800-1 demonstrate its potential as an electrode material for wide-ranging applications.