posted on 2022-01-20, 19:34authored byWenbin Jian, Wenli Zhang, Bingchi Wu, Xueer Wei, Wanling Liang, Xiaoshan Zhang, Fuwang Wen, Lei Zhao, Jian Yin, Ke Lu, Xueqing Qiu
The
low energy density and low cost performance of electrochemical
capacitors (ECs) are the principal factors that limit the wide applications
of ECs. In this work, we used enzymatic hydrolysis lignin as the carbon
source and an ammonia activation methodology to prepare nitrogen-doped
lignin-derived porous carbon (NLPC) electrode materials with high
specific surface areas. We elucidated the free radical mechanism of
ammonia activation and the relationship between nitrogen doping configurations,
doping levels, and preparation temperatures. Furthermore, we assembled
NLPC∥NLPC symmetric ECs and NLPC∥Zn asymmetric ECs using
aqueous sulfate electrolytes. Compared with the ECs using KOH aqueous
electrolyte, the energy densities of NLPC∥NLPC and NLPC∥Zn
ECs were significantly improved. The divergence of charge storage
characteristics in KOH, Na2SO4, and ZnSO4 electrolytes were compared by analyzing their area surface
capacitance. This work provides a strategy for the sustainable preparation
of lignin-derived porous carbons toward ECs with high energy densities.