Unraveling Lithium-Ion Transport in Solid Electrolyte Interphase: from Composition to Interface Dynamics via...

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Lithium-ion transport across the solid electrolyte interphase (SEI) is critical for lithium-ion battery (LIB) performance and stability.
• An atomic-level understanding of Li-ion transport through the SEI, including thermodynamic and kinetic parameters, remains incomplete.

Purpose of the Study:

• To systematically investigate the complete Li-ion transport process from the electrolyte through the SEI using molecular dynamics (MD) simulations.
• To identify the key factors governing Li-ion transport across different SEI components and interfaces.

Main Methods:

• Molecular dynamics (MD) simulations were employed.
• Simulations covered the electrolyte, organic/inorganic SEI components, and the electrolyte/organic SEI and organic SEI/inorganic SEI interfaces.

Main Results:

• Lithium ions in the organic SEI maintain either full or partial solvation shells.
• The highest energy barrier for Li-ion transport occurs at the organic-inorganic SEI interface.
• Complete Li-ion desolvation and structural disparities between organic and inorganic SEI layers contribute to the interfacial energy barrier.

Conclusions:

• The study provides a comprehensive free energy landscape for Li-ion transport across the SEI.
• Insights into the relationship between SEI composition, structure, and interfacial dynamics are offered.
• This work advances the understanding of factors limiting Li-ion battery performance.