Atomic Resolution of Solid-Electrolyte Interphase Formation via Off-Lattice On-the-Fly Kinetic Monte Carlo

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• The solid-electrolyte interphase (SEI) is critical for lithium metal battery stability.
• Understanding SEI formation mechanisms is key to battery optimization.
• Conventional Kinetic Monte Carlo (KMC) methods are limited for complex interfacial reactions.

Purpose of the Study:

• To develop and apply an advanced computational framework for atomic-level SEI growth investigation.
• To elucidate the SEI formation pathways in Li metal batteries.

Main Methods:

• An off-lattice on-the-fly KMC (OTF-KMC) method was developed.
• Machine learning force fields (MLFF) were integrated with OTF-KMC.
• Simulations focused on a Li(100) surface with ethylene carbonate (EC) and Li salts.

Main Results:

• Identified decomposition pathways for EC molecules and PF6- anions forming the SEI.
• Observed a distinct SEI structure: an inner inorganic layer and an outer organic layer.
• The simulated SEI structure aligns with experimental observations.

Conclusions:

• The proposed OTF-KMC with MLFF provides a robust framework for modeling interfacial reactions.
• This method offers atomic-level insights into SEI formation in Li metal batteries.
• The findings contribute to the rational design of high-performance batteries.