Reaction Center Shifting in Partially Fluorinated Electrolytes for Robust Lithium Metal Battery.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-metal batteries (LMBs) are crucial for high-energy density storage.
• Electrolyte formulation is key to extending LMB lifespan and performance.
• Achieving stable solid-electrolyte interphase (SEI) layers is a major challenge.

Purpose of the Study:

• To develop a compatible electrolyte for enhanced lithium-metal battery longevity.
• To investigate the role of electrolyte solvation structure on SEI formation.
• To evaluate the electrochemical performance of a novel partially fluorinated electrolyte.

Main Methods:

• Formulation of a partially fluorinated electrolyte with subdued Li+ solvation affinity.
• Electrochemical characterization including Li nucleation overpotential and cycling tests in Li||Li and Li||NCM811 cells.
• Analysis of SEI composition, focusing on LiF enrichment.

Main Results:

• The electrolyte promotes anion-driven SEI formation, resulting in a LiF-rich layer.
• Demonstrated effective Li+ transport kinetics and reduced Li nucleation overpotential (28 mV).
• Achieved high capacity retention (89.30% at 0.4C, 81.90% at 1C) and Coulombic efficiency (99.80% at 0.4C, 99.40% at 1C) over extended cycling in Li||NCM811 cells.

Conclusions:

• Weak-solvation interactions in partially fluorinated electrolytes are significant for LMB stability.
• Electrolyte solvent structure critically influences the formation of stable SEI layers.
• The developed electrolyte enables long-term stability and high-energy density in lithium-metal batteries.