Interfacial Structures in Ionic Liquid-Based Ternary Electrolytes for Lithium-Metal Batteries: A Molecular Dynamics...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Lithium-metal batteries offer high energy density but face challenges from dendrite formation and interfacial side reactions.
• Understanding lithium-metal surface/electrolyte interactions is key to improving battery performance and safety.

Purpose of the Study:

• To computationally investigate interfacial effects in ternary polymer electrolytes for lithium-metal batteries.
• To analyze how ionic liquids influence lithium-ion behavior and transport at the lithium-metal interface.

Main Methods:

• Atomistic simulations were employed to study poly(ethylene oxide) (PEO)-based electrolytes with lithium salts and various ionic liquids confined between lithium-metal slabs.
• Characterization of the local Li+ ion environment and transport properties in bulk and interfacial regions.

Main Results:

• Ion aggregation at the lithium-metal surface was observed, with structure and composition dependent on the ionic liquid.
• Small, flat ionic liquids promoted well-defined interfacial regions with high Li+ populations and diffusion.
• Large ionic liquids, like [P222mom]+, caused increased PEO density in the bulk due to steric effects at the interface.

Conclusions:

• The choice of ionic liquids in ternary polymer electrolytes can effectively tune interfacial structure-dynamics at the lithium-metal surface.
• This tuning capability allows for control over solid electrolyte interphase (SEI) formation, crucial for enhancing battery performance.