Combining Molecular Dynamics and Experimental Methods for the Parametrization of Binary Carbonate-Based Electrolytes

TL;DR

This study integrates molecular dynamics simulations with experimental measurements to accurately parameterize binary carbonate-based electrolytes for batteries, overcoming interphase effects that hinder traditional electrochemical methods.

Contribution

It introduces a combined approach of simulations and experiments to determine electrolyte parameters, improving accuracy for battery modeling.

Findings

Determined conductivity, transference number, thermodynamic factor, and diffusion coefficient for various electrolyte mixtures.

Validated simulated transference numbers using electrophoretic NMR spectroscopy.

Provided a more reliable parameter set for electrolyte modeling in battery research.

Abstract

Modelling the ionic transport in battery cells requires precise parametrization of the involved electrolytes. For carbonate-based electrolytes, however, the evaluation of their parameters suffers from interphase effects between the bulk electrolyte and the Li metal electrode, commonly present in the usual electrochemical polarization experiments. In this work, we combine measurements on conductivity and concentration cells with molecular dynamic simulations, avoiding these difficulties and thus, allowing for a more accurate determination of the parameters. We determine the conductivity, the transference number, the thermodynamic factor and the salt diffusion coefficient for three different electrolytes, i.e mixtures of ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl propionate (MP), dimethyl carbonate (DMC) and propylene carbonate (PC), containing LiPF$_6$ at various concentrations and temperatures. In order to validate the simulated transference numbers, we employ electrophoretic Nuclear Magnetic Resonance spectroscopy (eNMR).