An Atomistic Study of Reactivity in Solid-State Electrolyte Interphase Formation for Li/Li₇P₃S₁₁

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Lithium metal batteries (LMBs) offer higher energy density than graphite-based batteries.
• Solid-state electrolytes improve LMB safety, but interphase formation at the anode remains a challenge.
• Understanding the lithium metal anode-solid electrolyte interphase is critical for battery longevity.

Purpose of the Study:

• To develop a computational framework for exploring interphase formation at lithium metal anodes.
• To investigate the Li/Li7P3S11 solid-state electrolyte interface using advanced computational methods.
• To elucidate the mechanisms governing interphase growth and passivation.

Main Methods:

• High-throughput first-principles density functional theory (DFT) calculations.
• Machine-learning interatomic potentials (MLIPs) with automated iterative, active learning.
• Onsager transport theory for simulating time-dependent ionic diffusion.

Main Results:

• The framework accurately identifies thermodynamically stable interphase products (Li2S, LixP, Li3P) and their spatial distribution.
• Simulations reveal two reaction regimes (fast and slow diffusion) influencing phase formation rates.
• Cross-correlation effects in ionic motion significantly impact phosphorus diffusion and can lead to kinetic trapping.
• Interface passivation occurs as ionic fluxes approach zero, halting interphase growth.

Conclusions:

• The developed computational framework enables robust exploration of anode-electrolyte interphases.
• Understanding interphase dynamics is key to optimizing lithium metal anode stability.
• The findings provide insights into controlling interphase growth for safer, high-performance batteries.