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Title: Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions

We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (M. Z. Bazant, B. D. Storey, and A. A. Kornyshev, Phys. Rev. Lett., 106, 046102, 2011). Under very large charging currents, the cell potential shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface, allowing the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Furthermore, improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. Keywords: ionic
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [1]
  1. Clemson Univ., Clemson, SC (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Nevada, Las Vegas, NV (United States)
Publication Date:
OSTI Identifier:
1116487
DOE Contract Number:
AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physics. Condensed Matter; Journal Volume: 26; Journal Issue: 28
Publisher:
IOP Publishing
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ionic transport; electrical double layers; room-temperature ionic liquids; non-equilibrium transport; molecular dynamics