The Solvation Structure of Lithium Ions in an Ether Based Electrolyte Solution from First-Principles Molecular...

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Solvation and desolvation of lithium ions are critical in lithium-based secondary batteries.
• Oligoether (glyme) electrolytes are promising for lithium-ion, lithium-sulfur, and lithium-oxygen batteries.
• The precise solvation structure of lithium ions in glyme electrolytes remains unclear.

Purpose of the Study:

• To computationally investigate the solvation structure of lithium ions in triglyme and lithium bis(trifluoromethylsulfonyl)-amide (LiTFSA) mixtures.
• To clarify the microscopic interactions within glyme-based electrolytes.

Main Methods:

• Density functional theory (DFT) based molecular orbital (MO) calculations.
• Molecular dynamics (MD) simulations incorporating electronic structure information.

Main Results:

• Lithium ions are primarily solvated by curled triglyme molecules in an equimolar triglyme/LiTFSA mixture.
• Direct contact between lithium ions and TFSA anions was observed.
• Stable aggregates of lithium ions, TFSA anions, and triglyme molecules were identified, a novel finding compared to classical MD simulations.

Conclusions:

• The formation of lithium ion aggregates, even in small fractions, can significantly influence lithium ion transport.
• Electronic structure-based MD simulations are crucial for accurately elucidating detailed lithium ion solvation structures in electrolytes.