Layer-by-layer-stacked graphene/graphene-island supercapacitor

A large surface area and high electrical conductivity are required for an ideal supercapacitor electrode. Novel electrode materials have been investigated to obtain high volumetric and gravimetric capacitances with long cycling lifetimes. Graphene, a highly promising material for energy storage systems, has attracted considerable interest owing to its desirable characteristics such as large surface area and excellent electrical conductivity. However, the stacking of layers blocks the permeation of electrolytes and deteriorates the function of the electrode. Supercapacitor electrodes consisting of three-dimensional (3D) graphitic structures with large surface areas, high electrical conductivities, and low charge-transfer resistances, facile permeations, and diffusion paths for the electrolyte are required for portable electronic devices. In this study, we fabricate a 3D graphene structured electrode with graphene islands as spacers, which exhibits a non-Faradaic behavior and an ultrahigh power density of up to 187 kW/g.