Title

Charge Relaxation Dynamics of an Electrolytic Nanocapacitor

Authors

Authors

V. Thakore;J. J. Hickman

Comments

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Abbreviated Journal Title

J. Phys. Chem. C

Keywords

LATTICE BOLTZMANN METHOD; NUMERICAL-SOLUTION; CIRCUIT MODELS; ELECTRIC-FIELD; EQUATION; SIMULATION; EQUILIBRIUM; FLOWS; INTERFACE; ADVECTION; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, ; Multidisciplinary

Abstract

Understanding ion relaxation dynamics in overlapping electric double layers (EDLs) is critical for the development of efficient nanotechnology-based electrochemical energy storage, electrochemomechanical energy conversion, and bioelectrochemical sensing devices as well as the controlled synthesis of nanostructured materials. Here, a lattice Boltzmann (LB) method is employed to simulate an electrolytic nanocapacitor subjected to a step potential at t = 0 for various degrees of EDL overlap, solvent viscosities, ratios of cation-to-anion diffusivity, and electrode separations. The use of a novel continuously varying and Galilean-invariant molecular-speed-dependent relaxation time (MSDRT) with the LB equation recovers a correct microscopic description of the molecular-collision phenomena and enhances the stability of the LB algorithm. Results for large EDL overlaps indicated oscillatory behavior for the ionic current density, in contrast to monotonic relaxation to equilibrium for low EDL overlaps. Further, at low solvent viscosities and large EDL overlaps, anomalous plasmalike spatial oscillations of the electric field were observed that appeared to be purely an effect of nanoscale confinement. Employing MSDRT in our simulations enabled modeling of the fundamental physics of the transient charge relaxation dynamics in electrochemical systems operating away from equilibrium wherein Nernst-Einstein relation is known to be violated.

Journal Title

Journal of Physical Chemistry C

Volume

119

Issue/Number

4

Publication Date

1-1-2015

Document Type

Article

Language

English

First Page

2121

Last Page

2132

WOS Identifier

WOS:000348753000058

ISSN

1932-7447

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