Abstract
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 supercapacitors 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.
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•Lignin derived porous carbon is synthesized from self-template methods.•Lignosulfonate is modified to introduce more active sites.•The obtained porous carbon shows superior performance in supercapacitors.•Self-template is a promising method for porous carbons.