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United States Patent Application

View the Complete Application at the US Patent & Trademark Office
High surface area nano sized graphene and carbon compositions.
Do, Inhwan (East Lansing, MI), Kim, Hyunjoong (East Lansing, MI)
14/ 201,986
March 10, 2014
[0001] This invention was made with Government support under contract FA9453-12-M-0032 awarded by the United States Air Force. The Government has certain rights in the invention. [0002] This application claims priority from U.S. Provisional Patent application Ser. No. 61/786,733, filed Mar. 15, 2013. [0003] BACKGROUND OF THE INVENTION [0004] The instant invention deals with new compositions of matter. [0005] The invention uses high surface area nano sized graphene and carbon for capacitors, Graphene/carbon hybrid electrodes exhibit synergic effects on the performance enhancement of electrochemical capacitors. Both forms of activated carbon act as an active material and graphene acts as an active material. [0006] Activated carbons are materials commonly used in commercial electrochemical capacitors. However, they do not deliver sufficient performance necessary for applications requiring high energy and power density. This lack of performance is due to poor electrical conductivity and poor ion transport caused by very wide size distributions of randomly interconnected inner micropores. [0007] Graphene is used in electrochemical capacitors due to its high surface area, high mechanical and electrical properties, highly inert surface properties, low impurities, and the like. Nano sized graphene consists mostly of mesopores and macropores and thus the surface area of the nano sized graphene is accessible by even fairly large electrolyte ions. The nano sized graphene with surface areas of 600 m.sup.2/g shows very high specific capacitance outperforming the new carbon nanostructures such as single walled and double walled carbon nanotubes having comparable surface areas to nano sized graphene. [0008] The graphene reduces the cost of the electrode by replacing high cost activated carbon with lower cost graphene while improving energy storage by at least 5 to 20%. The graphene also acts as an ion migration catalyst to increase both energy and power density. Internal resistance is also reduced. [0009] The process and materials of this invention are different from any found in the prior art. The only reference that calls directly for using carbon black and graphene in an electrode together does so only to increase the conduction with a metal based active material. It is not shown or suggested that the active material is an activated carbon enhanced with graphene. [0010] Such a disclosure can be found in U.S. 2012/0088156A wherein the application teaches a multistep method to produce electrodes that includes adding graphene oxide to an electrode mixture and reducing the graphene oxide to graphene. One of the dependent claims includes adding less than 1% conductive, auxiliary agent that may be carbon black. The Invention [0011] Thus, what is disclosed and claimed herein as one embodiment is a composition of matter comprising a combination of a high surface area nano sized graphite and carbon. The graphites are nanosized graphene nanotubes and nanosized graphene nanoplatelets and the carbons can be for example, activated carbon, carbon black, and carbon nanofibers and carbon aerogels. [0012] Also, there is present in this invention a method for manufacturing a composition as set forth Supra. The process of manufacturing comprises dispersing graphene in a suitable solvent, dispersing carbon in a suitable solvent, combining and mixing the products together to form a slurry, filtering the slurry to provide a sheet form, drying the sheet, and, calendaring the sheet to a desired thickness and surface finish.