Lignin derived porous carbon with favorable mesoporous contributions for highly efficient ionic liquid-based supercapacitors

Lignin and its derivatives hold great potential in developing high performance porous carbon materials for supercapacitors due to the versatile features of high carbon content, abundant multifunctional groups, low cost, and environmental benefits. Unfortunately, their derived porous carbon generally has the features of unfavorable microporous-dominated morphologies and low specific surface area (SSA) attributed from the highly-branched structure of lignin, which are hardly suitable for the supercapacitors with ionic liquid (IL) electrolyte, leading to poor energy density and rate capability. Herein, porous carbon materials with desirable mesoporous contributions from sodium lignosulphonate are designed via a facile template method. Such rich mesoporisity carbon materials not only possess with three-dimensional interconnected network, large SSA, as well as favorable pore size distribution for accelerated ion and electron mass transfer, but also feature low heteroatom content for high electrochemical stability. Consequently, the optimal electrode exhibits a high capacitance of 166 F/g at 0.5 A/g, superior rate performance (59 Wh/kg at 59 kW/kg), as well as impressive cycle life with good capacitance retention of 93.1% in EMIBF₄ electrolytes. The present work opens a new avenue to design porous carbon materials with high mesopore properties from lignin for effective compatibility with IL electrolyte in high-performance supercapacitors.