A semiclassical Thomas-Fermi model to tune the metallicity of electrodes in molecular simulations

Abstract

Spurred by the increasing needs in electrochemical energy storage devices, the electrode/electrolyte interface has received a lot of interest in recent years. Molecular dynamics simulations play a proeminent role in this field since they provide a microscopic picture of the mechanisms involved. The current state-of-the-art consists in treating the electrode as a perfect conductor, precluding the possibility to analyze the effect of its metallicity on the interfacial properties. Here we show that the Thomas-Fermi model provides a very convenient framework to account for the screening of the electric field at the interface and differenciating good metals such as gold from imperfect conductors such as graphite. All the interfacial properties are modified by screening within the metal: the capacitance decreases significantly and both the structure and dynamics of the adsorbed electrolyte are affected. The proposed model opens the door for quantitative predictions of the capacitive properties of materials for energy storage.

arXiv comment10 pages, 10 figures (contains the SI)

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• Predicting the Charge Density Response in Metal Electrodes
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• Interfacial water asymmetry at ideal electrochemical interfaces
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• PiNNwall: Heterogeneous Electrode Models from Integrating Machine Learning and Atomistic Simulation
• Constant Chemical Potential-Quantum Mechanical-Molecular Dynamics simulations of the Graphene-electrolyte double layer
• A molecular perspective on induced charges on a metallic surface
• Frequency-dependent impedance of nanocapacitors from electrode charge fluctuations as a probe of electrolyte dynamics
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• Fully Periodic, Computationally Efficient Constant Potential Molecular Dynamics Simulations of Ionic Liquid Supercapacitors
• Brownian dynamics simulations of electric double-layer capacitors with tunable metallicity