Multi-scale self-templating synthesis strategy of lignin-derived hierarchical porous carbons toward high-performance zinc ion hybrid supercapacitors

Chemical activation is a common process for preparing porous carbon electrode materials of supercapacitors. Nevertheless, chemical activation approach has the disadvantages of being chemically caustic, environmentally unfriendly, and expensive. This study constitutes a multi-scale self-template approach for the preparation of lignin-derived hierarchical porous carbons (LHPCs) with high specific surface areas and excellent electrochemical performances. KCl, carbonates, and sulfates, generated in the carbonization process, play the role of multi-scale template agents for the pore-forming process. LHPCs exhibited superb electrochemical performances as electrodes of supercapacitors with alkaline and neutral sulfate electrolytes. In addition, the Zn//LHPCs hybrid supercapacitors (ZIHSCs) achieved an ultra-high energy density of 135 Wh kg(-1), which is 20 times higher than symmetric supercapacitors with KOH electrolytes (6.6 Wh kg(- 1)) and 9 times higher than symmetric super capacitors with Na2SO4 electrolyte (14.8 Wh kg(- 1)). This work proposes a general multi-scale self-template strategy for the synthesis of hierarchical porous carbons from sodium lignosulfonate for supercapacitor applications.

Automated summary

This study presents a multi-scale self-template approach for the synthesis of lignin-derived hierarchical porous carbon with high specific surface areas. The resulting carbon material exhibits excellent electrochemical performances as supercapacitor electrodes. Moreover, hybrid supercapacitors using this material achieved an ultra-high energy density, outperforming symmetric supercapacitors with different electrolytes.