Vertically Oriented Graphene Electrochemical Double Layer Capacitor with Very Fast Dynamic Response.

摘要

Activated carbon materials are expected to play a crucial role in supercapacitor technology. To date, they are the most preferred choice because they can be processed to have exceptionally high surface area, relatively high electric conductivity and are reasonably priced. This work was to improve the morphological structure of vertically oriented graphene (VOG), also called carbon nanosheets (CNS), to a higher density of taller sheets so that the total surface area is substantially increased, which increases capacitance, and more verticality to improve response time. An increase in the surface area of a factor of four resulted in only a factor of two increase in capacitance. Parametric studies in radio frequency plasma enhanced chemical vapor deposition (RF PECVD) growth and the use of gridded mesh on the substrate with a bias voltage provided higher density growth of the vertically oriented graphitic sheets. It was anticipated that, eventually, there would be a sheet density and sheet height that substantially impacts the dynamic response because of decreasing electrolyte conductance, but that was not yet observed.