Preparation of B/N co-doped carbon nanosheets and their electrochemical performance in Zn-ion redox capacitors

Abstract

The low energy density for conventional supercapacitors has limited their further application in a large scale. To enhance the energy density of supercapacitor, a novel redox Zn-ion supercapacitor is fabricated by using B, N codoped carbon nanosheets as cathode material and hydroquinone as redox electrolyte. The B, N co-doping is found to be beneficial for the enhanced electrochemical performance, and the introduced redox electrolyte has increased the capacitance of supercapacitor greatly. The B, N codoped carbon nanosheets shows a capacity of 168 mAhg−1 in the hydroquinone based redox electrolyte at 2 Ag−1, nearly 2 times as that (83 mAhg−1) in conventional Zn-ion electrolyte. Density functional calculation shows B, N- dual doping can increase the adsorption capability of carbon toward hydroquinone. This work shows that the combination of cathode material modification and redox electrolyte can enhance Zn-ion hybrid supercapacitor.