Structure and charging kinetics of electrical double layers at large electrode voltages
The structure and charging kinetics of electrical double layers (EDLs) at interfaces of NaCl solutions and planar electrodes are studied by molecular dynamics (MD) and Poisson–Nernst–Planck (PNP) simulations. Based on the MD results and prior experimental data, we show that counterion packing in planar EDLs does not reach the steric limit at electrode voltages below 1 V. In addition, we demonstrate that a PNP model, when complemented with a Stern model, can be effectively used to capture the overall charging kinetics. However, the PNP/Stern model can only give a qualitative description of the fine features of the EDL.
KeywordsMolecular Dynamic Simulation Stern Layer Molecular Dynamic Result Steric Limit Molecular Dynamic System
R.Q. thanks Professor Bazant at MIT for helpful discussions. The authors thank the Clemson-CCIT office for providing computer time. The Clemson authors acknowledge support from NSF under grant No. CBET-0756496. R.Q. was partly supported by an appointment to the HERE program for faculty at the Oak Ridge National Laboratory (ORNL) administered by ORISE. The authors at ORNL gratefully acknowledge the support from the Laboratory Directed Research and Development Program of ORNL and from U.S. Department of Energy under Contract No. DEAC05-00OR22725 with UT-Battelle, LLC at ORNL.
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