Reevaluating the Effect of a LiF-Containing Solid Electrolyte Interphase on Lithium Metal Anodes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• High-energy-density lithium metal batteries (LMBs) require stable solid electrolyte interphases (SEIs) for longevity.
• Lithium fluoride (LiF) is known to protect lithium metal anodes (LMAs), but the influence of its origin within the SEI is unclear.

Purpose of the Study:

• To investigate how different LiF sources (anion, solvent, native) affect SEI composition and properties in a fluoride-free electrolyte.
• To understand the role of LiF origin in SEI performance for advanced lithium metal batteries.

Main Methods:

• Systematic introduction of single fluorine sources into a fluoride-free electrolyte.
• Analysis of SEI composition and properties based on LiF origin.
• Evaluation of SEI performance during deep cycling of lithium metal anodes.

Main Results:

• SEI performance is influenced by both LiF content and coexisting organic components.
• Solvent-derived LiF-rich SEIs demonstrate superior LMA protection during deep cycling.
• These SEIs maintain structural integrity, suppress dead lithium formation, and enhance Coulombic efficiency.

Conclusions:

• LiF's protective mechanism is re-examined, highlighting the importance of its source.
• Understanding SEI chemistry based on LiF origin is critical for developing high-performance LMBs.