High Specific Energy Ultracapacitor with Hybrid Graphene Nanoplatelet Paper Electrodes

ABSTRACT: Ultracapacitors are attractive energy storage devices due to their high cycle life, extremely high charge/discharge rates, and very low degradation rates. Improving ultracapacitor specific energy to 30 W-hr/kg or more would provide important functional benefits enabling a wide variety of space-based and terrestrial systems. XG Sciences, Inc. (XGS), an industry leader in graphene product research and development with more than 10 years history through its partnership with Michigan State University, manufactures a new nanoparticle called xGnP Graphene Nanoplatelets. This"platelet morphology"lends itself to many unique applications that can take advantage of graphene"s unique mechanical, electrical, thermal and barrier properties. xGnP nanoplatelets are an ideal electrode material because they overcome the limitations of conventional electrodes delivering high surface area, high electrical conductivity, are more cost effective than other carbon nanomaterials, and are produced through a commercially-proven, environmentally friendly manufacturing process. XGS hybrid EC electrode compositions involving mixed morphologies of graphene and activated carbon have achieved 20 W-hr/kg. For this program, lightweight paper electrodes incorporating these hybrid xGnP and activated carbon with carbon nanotubes and/or xGnP serving as conductive"binder"are envisioned for ultracapacitors having the opportunity to deliver the 30+ W-hr/kg specific energy sought by the U.S. Air Force. BENEFIT: High energy density ultracapacitors enabled through use of novel paper electrodes constructed from hybrid xGnP(R)graphene platelets, activated carbon, using nanotube binders and stabilized for long life through optimized platelet oxygen functional groups will provide efficient, compact, reliable, long-life energy storage for space applications as well as terrestrial applications.