3D nanoporous graphene films converted from liquid-crystalline holey graphene oxide for thin and high-performance supercapacitors

Holey graphene oxide (HGO) is prepared and its liquid crystal (LC) formation in water is investigated. The blade-coated LC-HGO hydrogel is hydrothermally reduced to form 3D nanoporous films used as supercapacitor electrodes. Holey graphene sheets are rumpled and interconnected to form a cellular structure with pore size around 100 nm during the reduction process. Reduced HGO films with different thicknesses are integrated into solid-state symmetric supercapacitors and their electrochemical performances are studied. High specific capacitance up to 304 F g^-1 and high volumetric capacitance around 400 F cm^-3 are achieved from our thin and flexible devices.