The broader impact/commercial potential of this project is that due to the increased mobility of human beings and the nature of modern economic and social activities a variety of power challenges need to be addressed for portable electronic and mechanical devices. The needs include quick power delivery, light-weight but high-capacity energy storage, superior low-temperature operation and ability to handle millions of cycles. On average a soldier, a construction worker or an everyday handyman carry between 50 to 100lb of weight while they are working in their duty sites. A significant portion of this load is from the primary and backup batteries used for their tools and equipment, because corded delivery of power is not always possible. Computing, communication, biomedical and avionic industries are also constantly searching for light-weight but highly efficient energy storage gadgets. The ability to integrate graphene and carbon nanostructure based microsupercapacitors in the next generation energy delivery/storage solutions for portable devices and tools will open the doors for new education, research, product development and economic growth. Due to ultra-light-weight, transparency, extremely high thermal stability and tensile strength, and superior electrical conductivity graphene based supercapacitor would also be suitable for flexible, printable, transparent and wearable electronics.
This Small Business Technology Transfer (STTR) Phase I project plans to develop a non-Faradic, thin-film and electrochemical microsupercapacitor utilizing graphene and carbon nanotube (CNT) with high gravimetric energy density. The proposed microsupercapacitor would combine high energy storage capacity of batteries with high power delivery capability of regular capacitors. It would be compatible to commercial lithographic techniques and printable circuit technologies. A limiting factor in the miniaturization of the existing carbon-based supercapacitors is a relatively low volumetric energy density (VED) due to the poor packing density of structures like tangled CNTs. The VED of CNT-based supercapacitors is many orders of magnitude lower than the mainstream energy storage devices. The opportunity to miniaturize the supercapacitor exists with novel designs that strive to minimize its intrinsic components like electrodes and separators that do not directly contribute to cell energy storage. The proposed design would primarily use graphene nanoribbon (GNR) as electrode, which will not have the tangling issue of CNT. Due to the 2D flat nature of GNR the scaling and packing density of GNR devices would be extremely high. The long-term goal is to achieve an energy density over 100 Wh/kg using an array of the proposed microsupercapacitors.
