A novel strategy to achieve 2V symmetric supercapacitor using B, N doped rGO as an electrode material in “water in salt based hydrous electrolyte”

Abstract

Design of solid-state symmetric supercapacitors (SSCs) with superior power density, energy density and long cycle life using carbonaceous electrode materials in aqueous electrolyte media remains a great challenge. A high working potential window of SSC-based on aqueous electrolyte can be achieved by “trapping” free water molecules. Herein, the Lewis acid/base characteristic of B & N-doped reduced graphene oxide was synthesized through hydrothermal process and utilized for solid-state SSC fabrication. A solid-state electrolyte composed of polyethylene glycol (PEG) as water trapping agent and sodium dodecyl sulfate as ionic conductivity improving agent are used for solid-state SSC fabrication. The ethylene oxide unit of PEG polymer chains tightly binds the free water molecules and provides thermodynamic stability. This hydrous electrolyte offers ~2 V electrochemical potential windows to the SSC device which is greater than the normal aqueous electrolyte. The SSC device based on hydrous electrolyte showed maximum ~10.58 kW kg−1 power density and ~43.33 W h kg−1 energy density. In addition, the superior life cycle of ~97.85% specific capacitance retention was obtained after 10,000 continuous charge/discharge cycles at 5 A g−1 current density.