Insight into the Li$_2$CO$_3$-K$_2$CO$_3$ eutectic mixture from classical molecular dynamics: thermodynamics, structure and dynamics

TL;DR

This study develops a new classical force field for Li$_2$CO$_3$-K$_2$CO$_3$ eutectic mixture, enabling efficient molecular dynamics simulations to explore its thermodynamics, structure, and ion transport properties across various temperatures and pressures.

Contribution

A novel non-polarizable force field for Li$_2$CO$_3$-K$_2$CO$_3$ eutectic mixture was created and validated for long-timescale molecular dynamics simulations.

Findings

Force field accurately reproduces experimental thermodynamic data.

Ion diffusion and viscosity depend strongly on temperature and pressure.

Molecular insights into melt structure and ion transport mechanisms.

Abstract

In this work, we use molecular dynamics simulations to study the thermodynamics, structure and dynamics of the Li$_2$CO$_3$-K$_2$CO$_3$ (62:38 mol%) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations as reference data. This simple force field allows efficient molecular simulations of phenomena at long timescales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self diffusion coefficients, viscosity and ionic conductivity.