Spatiochemical Segregation in Porous Lithium-Metal Interphases

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• The solid-electrolyte interphase (SEI) is crucial for lithium metal battery performance.
• Understanding SEI formation during lithium plating/stripping is vital but poorly understood.

Purpose of the Study:

• To investigate the spatiochemical evolution of the SEI during lithium plating and stripping.
• To elucidate the relationship between SEI chemistry, architecture, and mechanical behavior.

Main Methods:

• Utilized a 1,2-dimethoxyethane (DME)/1 M lithium bis(fluorosulfonyl)imide (LiFSI) electrolyte system.
• Employed correlative X-ray photoelectron spectroscopy, SEM, NanoSIMS, and synchrotron X-ray absorption spectroscopy.

Main Results:

• Observed spatiochemical segregation of SEI products into heterogeneous domains.
• Identified enrichment of LiF-dominated inorganic species spatially decoupled from oxygen-containing phases.
• Demonstrated mechanical reorganization into a porous, electrolyte-retaining framework during stripping.

Conclusions:

• SEI evolution is governed by coupled chemo-mechanical processes.
• Spatiochemical segregation dictates SEI composition, architecture, and permeability.
• Findings suggest strategies to improve SEI stability and electrolyte retention in lithium-metal batteries.