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 m 2 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.