Template-free synthesis of lignin-derived 3D hierarchical porous carbon for supercapacitors

A facile synthesis strategy for lignin-derived three-dimensional hierarchical porous carbon (LHPC) was developed in this work. The LHPC was synthesized by a one-step carbonization-activation process using lignin as a carbon precursor and wet KOH as an in situ chemical activation agent. Compared with dry KOH activation agent, the wet KOH shows exfoliation effect on assisting the formation of hierarchical porous structure of LHPC. The H2O plays a key role of an exfoliation agent in forming the hierarchical porous structure of LHPC. The as-prepared LHPC shows a high specific surface area of 2109 m2 g−1 and hierarchical pores. When used as an electrode material for supercapacitor, the LHPC exhibits excellent electrochemical performances, including a high capacitance of 254 F g−1 at 0.5 A g−1 and excellent rate capability with 59% capacitance retention at 20 A g−1. This study offers a convenient and practical approach to produce a high-rate hierarchical porous carbon material for supercapacitors.