3D boron/nitrogen dual doped layered carbon for 2 V aqueous symmetric supercapacitors

The operating voltage for supercapacitors (SCs) in alkaline electrolyte was limited by the splitting of water. Therefore, it is still a huge challenge to obtain high energy density by improving the operating voltage for aqueous symmetric SCs. Herein, a novel strategy is developed to construct the 3D boron/nitrogen dual doped layered carbon (BNLC) by using the in-situ potassium tetraborate activation from biomass. The synergetic effects of B/N heteroatoms and 3D layered structures enhance the electron transport property, and achieve the high voltage window of 2 V for SCs in 3 M Zn(CF3SO3)(2) aqueous electrolyte. As a result, the BNLC presents high specific capacitance of 315.3 F g(-1) at 0.05 A g(-1), good rate performance of 241.1 F g(-1) at 40 A g(-1) and excellent cycle stability with 98.4% of initial capacitance after 20,000 cycles. In addition, the energy density of BNLC-based SC in neutral electrolyte (43.8 Wh kg(-1)) is 4.4 times as high as that of BNLC-based SC in alkaline electrolyte (9.9 Wh kg(-1)). This work pioneers an efficient strategy for the use of the synergetic effects of heteroatoms and neutral electrolyte to enhance the energy density of energy storage devices. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A novel strategy using potassium tetraborate from biomass was developed to construct 3D boron/nitrogen dual doped layered carbon (BNLC) in 3 M Zn(CF3SO3)(2) aqueous electrolyte, achieving a high voltage window of 2 V for supercapacitors. The BNLC showed high specific capacitance, good rate performance, and excellent cycle stability, with an energy density in neutral electrolyte that is 4.4 times higher than in alkaline electrolyte.