High-performance pseudocapacitors from kraft lignin modified active carbon

In this study, Kraft lignin (KL) modified HNO3-treated active carbon (KL/TAC) materials were prepared by using a facile ultrasonical-assisted deposition method and its application as supercapacitor electrode materials was studied. The synergetic effect of HNO3 treatment and KL coupling can significantly enhance the electrochemical activity of active carbon (AC), leading to a high specific capacitance (293 F g(-1) at a current density of 1 A g(-1)) of the as-prepared KL/TAC material, which is much higher than that of HNO3-treated active carbon (TAC, 120 F g(-1)) and KL modified active carbon (KL/AC, 118 F g(-1)). The quantitative analysis of CV curves verified that the high capacitance of KL/TAC is mainly attributed by the pseudocapacitance enhancement due to the redox reactions of quinone groups in KL molecules. The continuous charge/discharge cycling test demonstrated the good electrochemical stability of the KL/TAC materials. Therefore, the KL/TAC composite prepared in this work is a promising electrode material for supercapacitors due to its excellent electrochemical performance and inherent renewable nature. (C) 2019 Elsevier Ltd. All rights reserved.