Electric Double Layers At the Interface of Ionic Liquids/Onion-Like Carbon: Capacitance Enhancement Originating From Spherical Curvature

Wednesday, October 19, 2011: 8:35 AM
101 A (Minneapolis Convention Center)
Guang Feng, Department of Chemical & Biomolecular Engineering, Vanderbitl University, Nashville, TN, De-en Jiang, Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN and Peter T. Cummings, Center of Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN

Recent experiments indicate that onion-like carbon (OLCs) can be used as the electrodes in supercapacitors to increase their energy density and charging/discharging rates.[1] To understand the physical origin of such observations, molecular dynamics simulations were performed for an IL of [emim+][TFSI-] near idealized spherical carbon onions. We investigated the structure and capacitance of electrical double layers (EDLs) in ILs outside these OLCs with radii ranging from 0.356 nm – 1.223nm. We quantified the structure of EDLs near the OLCs and computed their capacitance. The scaling of capacitance with respect to the radius of OLC exhibits a qualitative agreement with experimental observations. We attribute the enhancement of capacitance over planar surfaces to the curvature of OLCs.

 [1] D. Pech, M. Brunet, H. Durou, P. Huang, V. Mochalin, Y. Gogotsi, P.L. Taberna and P. Simon, Nature Nanotech. 2010, 5, 651.

* To whom correspondence should be addressed. E-mail: peter.cummings@vanderbilt.edu

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