278506 Simulation of Propylene Carbonate As Solvent for Electrochemical Double-Layer Capacitors

Friday, November 2, 2012: 8:35 AM
413 (Convention Center )
Xinli You1, Lawrence R. Pratt1 and Noshir Pesika2, (1)Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, (2)Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA

Simulation of Propylene Carbonate as Solvent for

Electrochemical Double-layer Capacitors

X. You, L. R. Pratt, and N. Pesika

Abstract    Propylene carbonate (PC) is a popular choice of solvent for electric double-layer capacitors (EDLCs).1,2 Despite recent encouraging simulations of EDLCs3 based on carbon nanotube forests, thorough testing of the required force-field features has not been available. Recent work3,4 shows that the modeled liquid PC completely wets a planar graphite surface (contact angle,  =0), in disagreement with experimental droplet formation ( =37). Empirical adjustment of PC:graphite attractive interactions brings those results into agreement. Molecular dynamics simulations of PC droplets, bulk PC liquid, and a saturated solution of tetraethylammonium tetrafluoroborate in PC, using the GROMACS package, further characterize the assumed force-field. We present and discuss a range of interfacial properties including surface tensions, and their temperature and concentration dependences. We consider the applicability of the Kelvin equation, describing the vapor pressure of small droplets, for evaluating the curvature dependence of surface tension. 5

FIG: (left) Interfacial density profiles and simulation geometry for slab calculation of 1000 PC with 85 tetraethylammonium and 85 tetrafluoroborate at 300K. Compared with pure PC (surface tension = 40.8erg/cm2), the ionic material increases the surface tension to 41.5erg/cm2.  (right) Simulation configuration of a droplet with 600 PC molecules.

1.      Yang, L., Fishbine, B. H., Migliori, A., and Pratt, L. R. J. Am. Chem. Soc, 131, 12373 (2009).

2.      Yang, L., Fishbine, B. H., Migliori, A., and Pratt, L. R. J. Chem. Phys. 132, 044701 (2010).

3.      W. Zhang, G. G. Hoffman1, L. R. Pratt1, N. Pesika1, K. M.  Aritakula2 and S. W. Rick2(1Tulane University, 2University of New Orleans 2012)

4.      "Simulation of Propylene Carbonate as Solvent for Electrochemical Double-layer Capacitors", Hoffman, G. G., Mariano, R., Pesika, N., Pratt, L. R., Rick, S. W., and X. You (Proc. LA EPSCoR RII LA-SiGMA 2011 Symp.), p 101-104.

5.      Powles, J. G., Fowler, R. F., and Evans, W. A. B. Chem. Phys. Letts. 76, 289 (1983).


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See more of this Session: Interfacial Phenomena in Ionic Liquids
See more of this Group/Topical: Engineering Sciences and Fundamentals