Morphology and structure control of lignin-derived hierarchical porous carbon for high-performance supercapacitors

Abstract

Lignin-derived porous carbon (LDPC) is a low-cost and sustainable electrode material for supercapacitors. However, the complex three-dimensional amorphous structure of lignin brings challenges to the morphology and structure control of LDPC, which limits the electrochemical performance of these electrodes. Herein, a series of LDPCs with different particle morphologies and hierarchical pore structures are prepared by spray drying and KOH activation. It is found that the morphology and structure of LDPCs can be effectively controlled by adjusting the spray drying temperature and KOH ratio. A systematic investigation has been conducted on the relationship between the morphology and structure of LDPCs and their electrochemical performance. The preferred LDPC exhibits excellent electrochemical performance, showing high specific capacitances of 372.5 F g−1 and 264.8 F g−1 at current densities of 0.2 A g−1 and 20 A g−1, respectively, in the three-electrode test. The symmetric supercapacitor assembled with the LDPC electrode material exhibits superior cycling stability and energy density. After 10000 cycles of continuous charging and discharging at current density of 1 A g−1, the specific capacitance retention is as high as 96.4%. When the power density is 493.3 W kg−1, the energy density reaches ∼9.1 Wh kg−1. This work offers a viable method for regulating the morphology and structure of LDPC electrode material for high-performance supercapacitor application.