Graphene-based composite supercapacitor electrodes with diethylene glycol as inter-layer spacer

Diethylene-glycol/graphene nano-composites were produced by a simple mild solvothermal method, in which diethylene glycol was grafted onto the surfaces of reduced graphene oxides (RGO) as an inter-layer spacer to spatially separate graphene sheets, i.e. to prevent the aggregation of graphene single sheets. The presence of diethylene glycol was confirmed by several characterizations, including IR, XPS, and AFM. Because of the chain length and electrolyte affinity of the diethylene glycol spacer, most of the surface area of graphene single layer sheets could be accessed by electrolyte, leading to high capacity as supercapacitor electrodes with an impressive electrochemical capacitance (237.8 F g(-1) at a charging current of 0.1 A g(-1)), outstanding rate performances (182.9 F g(-1) at 20 A g(-1)), and excellent cycling stabilities (less than 5 and 10% decline after 2000 and 10 000 cycles). The diethylene-glycol/graphene nano-composites are thus particularly promising for "high-power densities" and "long cycle life" supercapacitor electrodes.