REDUCED GRAPHENE OXIDE HYDROGELS, DEPOSITED IN NICKEL FOAM BY ELECTROPHORETIC DEPOSITION, FOR SUPERCAPACITOR

Supercapacitors, a class of electrochemical energy storage devices with superior power densities and long cycling lifetimes, have attracted great attention for the last decade due to their widespread application in backup power supply systems, portable devices, power tools, and hybrid electric vehicles. Graphene is considered as an ideal supercapacitor electrode material due to its large surface area, superior electrical conductivity, good chemical stability, and high mechanical strength. The theoretical specific capacitance of graphene is as high as ~ 550 F/g. The assembly of graphene sheets into three-dimensional interconnected porous microstructures, namely graphene hydrogels, has been considered the most effective approach to utilize these materials in supercapacitors that can achieve high specific capacitances. However, graphene hydrogels typically consist of large amount of water, up to 99 wt. %, resulting in very low graphene packing density. Therefore, the usual volumetric capacitance of graphene hydrogels is very poor, limiting their practical application.Please click Additional Files below to see the full abstract.