beta-Ni(OH)(2)/nickel-cobalt layered double hydroxides coupled with fluorine-modified graphene as high-capacitance supercapacitor electrodes with improved cycle life

摘要

As energy consumption grows, the demand for a new generation of high-security, long-life and large-capacity power supplies is growing rapidly. Here we demonstrate a facile and binder-free strategy to obtain beta-Ni(OH)(2)/nickel-cobalt layered double hydroxides (beta-Ni(OH)(2)/NiCo-LDH) coupled with fluorine-modified graphene (FG) as supercapacitor electrodes (beta-Ni(OH)(2)/NiCo-LDH@FG) via hydrothermal method, synchronous electrochemical exfoliation of graphite into fluorine-modified graphene and assembly on beta-Ni(OH)(2)/NiCo-LDH. This hybrid structure of beta-Ni(OH)(2)/NiCo-LDH and modified graphene as supercapacitor electrode displays high conductivity, high ion diffusivity and strong mechanical strength. As a result, the beta-Ni(OH)(2)/NiCo-LDH@FG electrode possesses excellent capacitance (3996 mF cm(-2) at 1 mA cm(-2)), remarkable rate capability and improved cycle life. The beta-Ni(OH)(2)/NiCo-LDH coupled with undoped electrochemically exfoliated graphene exhibits the significantly improved cycle stability (79% capacitance retention after 1000 cycles at 5 mA cm(-2)), superior to that of beta-Ni(OH)(2)/NiCo-LDH (31%). Therefore, this strategy has great potential to improve the performance of electrodes. (C) 2021 Elsevier B.V. All rights reserved.