Fluorinated Aromatic Diluent for High-Performance Lithium Metal Batteries

Area of Science:

• Electrochemistry
• Materials Science

Background:

• High-concentration electrolytes show promise for lithium metal battery cyclability.
• Material cost and practicality of high-concentration electrolytes remain challenges.

Purpose of the Study:

• To investigate 1,2-difluorobenzene as a diluent solvent to achieve a high-concentration effect in electrolytes.
• To enhance the performance and stability of lithium metal batteries.

Main Methods:

• Utilized 1,2-difluorobenzene as a diluent solvent in electrolytes.
• Analyzed the lowest unoccupied molecular orbital (LUMO) energy level and binding affinity for lithium ions.
• Incorporated triple salts to prevent aluminum current collector corrosion.
• Examined the composition of the solid-electrolyte-interphase (SEI) layer.

Main Results:

• 1,2-difluorobenzene induced a high-concentration effect at a bulk salt concentration near 2 m.
• The solid-electrolyte-interphase (SEI) layer was modified to be rich in lithium fluoride (LiF).
• Triple salts effectively prevented aluminum current collector corrosion, improving cycling performance.

Conclusions:

• 1,2-difluorobenzene enables a local high-concentration effect with reduced bulk salt concentrations.
• This strategy offers a design principle for cost-effective and high-performance lithium metal batteries.
• The modified SEI layer and protected current collector contribute to enhanced battery cyclability.