Multi-scale modelling of supercapacitors: From molecular simulations to a transmission line model

TL;DR

This paper combines molecular dynamics simulations with a transmission line model to accurately predict supercapacitor charging behavior, bridging microscopic properties and macroscopic device performance.

Contribution

It introduces a multi-scale modeling approach that integrates molecular simulations with a transmission line model for supercapacitors, validated against non-equilibrium MD data.

Findings

Transmission line model accurately predicts supercapacitor charging.

Molecular simulations determine thermodynamic and transport properties.

Model aligns well with electrochemical impedance experiments.

Abstract

We perform molecular dynamics simulations of a typical nanoporous-carbon based supercapacitors. The organic electrolyte consists in 1-ethyl-3-methyl--imidazolium and hexafluorophosphate ions dissolved in acetonitrile. We simulate systems at equilibrium, for various applied voltages. This allows us to determine the relevant thermodynamic (capacitance) and transport (in-pore resistivities) properties. These quantities are then injected in a transmission line model for testing its ability to predict the charging properties of the device. The results from this macroscopic model are in good agreement with non-equilibrium molecular dynamics simulations, which validates its use for interpreting electrochemical impedance experiments.