Molecular dynamics simulation of LiTFSI-acetamide electrolytes: structural properties

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Nonaqueous electrolytes are vital for advanced battery technologies.
• Understanding ion coordination and liquid structure is key to optimizing electrolyte performance.
• Lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and acetamide are common electrolyte components.

Purpose of the Study:

• To investigate the liquid structures of LiTFSI-acetamide electrolytes using molecular dynamics simulations.
• To determine the coordination preferences of Li+ cations and TFSI- anions.
• To analyze the effect of varying LiTFSI/acetamide molar ratios (1:2, 1:4, 1:6) on electrolyte structure and homogeneity.

Main Methods:

• Molecular dynamics (MD) simulations were employed to model electrolyte systems.
• Analysis focused on ion coordination, anion conformations, and cluster formation.
• Investigated systems with LiTFSI/acetamide molar ratios of 1:2, 1:4, and 1:6.

Main Results:

• Li+ cations preferentially coordinate with sulfonyl oxygens of TFSI- anions and carbonyl oxygens of acetamide.
• TFSI- anions exhibit cis, trans, and gauche conformations, with gauche dominating at higher concentrations.
• The 1:4 LiTFSI/acetamide ratio resulted in a more homogeneous liquid structure compared to 1:2 and 1:6 ratios.

Conclusions:

• Acetamide effectively relaxes the electrolyte structure, improving homogeneity.
• The 1:4 molar ratio demonstrates optimal structural properties for nonaqueous electrolytes.
• Findings provide insights into electrolyte design for enhanced electrochemical device performance.