A bidirectional strategy of pore-creating and surface modification towards lignin-based carbon aerogels for enhanced energy storage

The easily accessible porous structure and appetency to the electrolyte directly affect the electrochemical properties of carbon electrode materials. Here, a bidirectional pore-creating/regulation and surface modification strategy is proposed to construct functional nitrogen/sulfur-doped lignin-based porous carbon aerogels with hierarchical interconnected porous structure. Firstly, nitrogen and sulfur-rich aerogels containing K 2 CO 3 with an interconnected network structure was prepared by a simple one-pot method. In the pyrolysis process, activated mediates for KOH, thiourea and K 2 CO 3 with different pore-forming functions decomposed, and then hierarchical pore creation and in situ heteroatom doping were accomplished simultaneously in this process. The N, S co-doped porous carbon aerogels showed a high specific surface area (2933 m 2  g −1 ) and a large pore volume (1.87 cm 3  g −1 ). The hierarchical porous structure of the micro-mesoporous interconnects enabled fast ion/electron transport and the ultra-micropores further increased the specific capacitance, N, S-doped (nitrogen content of 1.0 %, sulfur content of 2.4 %) improved hydrophily of carbon materials and enhanced the adsorption capacity of electrolyte ions, resulting in carbon aerogels displayed a high specific capacitance of 330 F g −1 at 0.5 A g −1 . The assembled supercapacitor device showed excellent capacitance retention (81 %) and a high energy density of 10.1 Wh kg −1 . This work provides guidance for rationally designing the pore structure and active surface for supercapacitors carbon electrodes.