Hierarchical nanoarchitectonics of ordered mesoporous carbon from lignin for high-performance supercapacitors

The synthesis of ordered mesoporous carbons (OMCs) with hierarchical pore structure is significant for supercapacitor applications as electrode material. In this study, the ordered mesoporous carbons with hierarchical pore structure (HOMC) are synthesized via solvent evaporation induced self-assembly (EISA) method using lignin from walnut shell as carbon precursor and Co²⁺ ion as crosslinking agent, followed by removal of metal by diluted acid and chemical activation with KHCO₃. The prepared HOMC material has a large specific surface area of 2033 m² g^-1 and high pore volume of 1.59 cm³ g^-1, and it shows good electrochemical performance as the electrode of supercapacitor with high specific supercapacitances of 286 and 206 F g^-1 in 6 M KOH aqueous solutions at 0.2 and 20 A g^-1, respectively. The assembled HOMC-based symmetric supercapacitors provides a specific energy density of 13.5 Wh kg^-1 at a high power density of 44.3 kW kg^-1 and keep good cycling stability after 5000 cycle tests. The superior electrochemical performance is ascribed to the long range ordered parallel mesoporous channels, hierarchical porous structure, high specific surface area and appropriate microporous/mesoporous ratio. The materials prepared in this study have the potential to be used in the fields of adsorption, energy storage and capacitance deionization.