Abstract: Disclosed is a carbon material that can be useful, for example, in ultracapacitors. Also disclosed are applications and devices containing the carbon material.

Abstract: Disclosed is a carbon material that can be useful, for example, in ultracapacitors. Also disclosed are applications and devices containing the carbon material.

Abstract: Disclosed are compositions and methods wherein graphite oxide was exfoliated and dispersed in propylene carbonate (PC) by bath sonication. Heating the graphene oxide suspensions at 150° C. significantly reduced the graphene oxide platelets; paper samples comprised of such reduced graphene oxide platelets had an electrical conductivity of 5230 S/m. By adding TEA BF4 to the reduced graphene oxide/PC slurry and making a 2-cell ultracapacitor, specific capacitance values of about 120 F/g were obtained.

Abstract: One embodiment of the current disclosure provides an ultracapacitor including at least one graphene-based electrode, an electrolyte containing an ionic liquid, and a dielectric separator dividing the ultracapacitor into two chambers, each chamber containing an electrode and a portion of the electrolyte. In another embodiment, the graphene has been expanded by exposure to microwave radiation then chemically activated. Another embodiment of the current disclosure provides an electrochemical energy storage device containing such an ultracapacitor. Still other embodiments of the disclosure relate to ionic liquids, some of which may be suitable for use in an ultracapacitor, methods of synthesizing such liquids, and methods of designing such liquids. Further embodiments relate to methods of using ultracapacitors, for example in automobiles, power grids, high-temperature applications, and other applications.