Friday, April 25, 2014

Paper-based ultracapacitors with carbon nanotubes-graphene composites

As reported by EE Times: Ultracapacitors, also called supercapacitors, serve as temporary energy storage that can quickly charge and discharge for everything from regenerative brakes in electric vehicles to cordless power tools that recharge in 90 seconds to stabilizing computer power supplies. Now researchers at George Washington University's Micro-Propulsion and Nanotechnology Laboratory report that superior ultracapacitors can be constructed from an inexpensive hybrid composite of graphene flakes mixed with single-walled carbon nanotubes.
Full report can be found in the JAP paper below
Prototype of an ultracapacitor device based on carbon nanostructures.

Paper-based ultracapacitors with carbon nanotubes-graphene composites
Jian Li, Xiaoqian Cheng, Jianwei Sun, Cameron Brand, Alexey Shashurin, Mark Reeves and
Michael Keidar
J. Appl. Phys. 115, 164301 (2014);

In this paper, a paper-based ultracapacitors were fabricated by the rod-rolling method with the ink of carbon nanomaterials, which were synthesized by arc discharge under various magnetic conditions. Composites of carbon nanostructures, including high-purity single-walled carbon nanotubes (SWCNTs) and graphene flakes were synthesized simultaneously in a magnetically enhanced arc. These two nanostructures have promising electrical properties and synergistic effects in the application of ultracapacitors. Scanning electron microscope, transmission electron microscope, and Raman spectroscopy were employed to characterize the properties of carbon nanostructures and their thin films. The sheet resistance of the SWCNT and composite thin films was also evaluated by four-point probe from room temperature to the cryogenic temperature as low as 90 K. In addition, measurements of cyclic voltammetery and galvanostatic charging/discharging showed the ultracapacitor based on composites possessed a superior specific capacitance of up to 100 F/g, which is around three times higher than the ultracapacitor entirely fabricated with SWCNT.

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