Lithium Ion Transport Mechanism in Ternary Polymer Electrolyte-Ionic Liquid Mixtures: A Molecular Dynamics Simulation...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Ternary polymer electrolytes (PEO20LiTFSI with PYR13TFSI) show enhanced lithium mobility compared to binary systems.
• Understanding the microscopic mechanisms behind this enhanced mobility is crucial for battery development.

Purpose of the Study:

• To investigate the lithium transport mechanism in ternary polymer electrolytes using molecular dynamics (MD) simulations.
• To elucidate the role of ionic liquids in enhancing lithium ion mobility within polymer electrolytes.

Main Methods:

• Employed MD simulations to study lithium transport in PEO20LiTFSI/PYR13TFSI systems.
• Utilized an analytical Rouse-based cation transport model to analyze transport mechanisms.
• Predicted lithium diffusion coefficients and compared simulation data with experimental findings.

Main Results:

• Lithium ions remain primarily coordinated by polyethylene oxide (PEO) chains in ternary electrolytes.
• Ionic liquid molecules do not directly enhance lithium transport.
• The plasticizing effect of the ionic liquid increases PEO chain dynamics, leading to higher lithium mobility.

Conclusions:

• The enhanced lithium mobility in these ternary electrolytes is attributed to the improved dynamics of the PEO chains facilitated by the ionic liquid.
• The applied Rouse-based model demonstrates broad applicability for analyzing transport in polymer electrolytes.