Unusual battery type pseudocapacitive behaviour of graphene oxynitride electrode: High energy solid-state asymmetric supercapacitor

摘要

Introduction of heteroatom provides pseudocapacitive behaviour, increasing specific capacitance of carbon-based electrodes. We developed a redox-active nitrogen grafted graphene oxinitride (GON) molecular heterostructures by hydrothermal reactions of GO with ammonia solution. The multiscale chemical and physical characterization of GON confirmed the presence of nitrogen and oxygen entities which provides enormous redox reaction leading to superior electrochemical pseudocapacitance. Significantly, GON exhibited the highest specific capacitance of 783.5 F g(-1) at 1 A g(-1) ever reported for carbon family with very good capacitance retention (94.6%) upto 10,000 consecutive charge-discharge cycles at 10 A g(-1). Further, GON asymmetric supercapacitor displayed an outstanding energy density of 40.5 Wh/kg at power density of 900 W/kg in PVA/KOH gel electrolyte. The device also exhibited an admirable rate capability, energy density 9.5 Wh/kg at a power density of 8526 W/kg together with a long term stability (87%) up to 5,000 cycles. (C) 2020 Elsevier B.V. All rights reserved.