Charge Transfer in Ultrafine LDH Nanosheets/Graphene Interface with Superior Capacitive Energy Storage Performance

Abstract

Two-dimensional LDH nanosheets recently have generated considerable interest in various promising applications because of their intriguing properties. Herein, we report a facile in situ nucleation strategy toward in situ decorating monodispersed Ni–Fe LDH ultrafine nanosheets (UNs) on graphene oxide template based on the precise control and manipulation of LDH UNs anchored, nucleated, grown, and crystallized. Anion-exchange behavior was observed in this Ni–Fe LDH UNs@rGO composite. The Ni–Fe LDH UNs@rGO electrodes displayed a significantly enhanced specific capacitance (2715F g –1 at 3 A g –1 ) and energy density (82.3 Wh kg –1 at 661 W kg –1 ), which exceeds the energy densities of most previously reported nickel iron oxide/hydroxides. Moreover, the asymmetric supercapacitor, with the Ni–Fe LDH UNs @rGO composite as the positive electrode material and reduced graphene oxide (rGO) as the negative electrode material, exhibited a high energy density (120 Wh kg –1 ) at an average power density of 1.3 kW kg –1 . A charge transfer from LDH layer to graphene layer, which means a built in electric field directed from LDH to graphene can be established by DFT calculations, which can significantly accelerate reaction kinetics and effectively optimize the capacitive energy storage performance.