Phase Separation and Ion Diffusion in Ionic Liquid, Organic Solvent, and Lithium Salt Electrolyte Mixtures

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Ternary mixtures of ionic liquids, organic solvents, and metal salts offer desirable properties for electrothermal energy systems.
• Understanding the phase behavior of these complex electrolytes is crucial for optimizing their performance.

Purpose of the Study:

• To investigate the effect of ionic liquid composition on the phase behavior of ternary electrolyte mixtures.
• To determine the key factors governing phase separation in these systems.

Main Methods:

• Large-scale classical molecular dynamics simulations of 10 different ternary electrolyte mixtures.
• Density functional theory calculations to determine pairwise binding energies.
• Simulations conducted across a temperature range of 260–500 K.

Main Results:

• Phase separation in these electrolytes is primarily governed by the pairwise binding energy of mixture constituents.
• The transition temperature for phase separation directly correlates with the pairwise binding energy of ionic liquid pairs.
• In some cases, increased temperature led to decreased Li+ ion diffusion due to condensed ionic domains.

Conclusions:

• Pairwise binding energy is a critical parameter for predicting and controlling phase separation in multicomponent electrolytes.
• The study offers insights into designing novel electrolyte mixtures for diverse energy applications.
• Understanding ion dynamics and phase behavior is key for advancing energy storage technologies.