Fluorinated solid electrolyte interphase enables highly reversible solid-state Li metal battery.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state electrolytes (SSEs) offer enhanced safety and energy density for batteries.
• However, lithium dendrite growth and lower critical current density in SSEs limit their practical application.
• Nonaqueous liquid electrolytes face challenges with dendrite formation and safety.

Purpose of the Study:

• To suppress lithium dendrite growth in solid-state electrolytes.
• To improve the critical current density and electrochemical stability of SSEs.
• To enable the use of high-voltage cathodes for enhanced battery energy density.

Main Methods:

• In situ formation of a lithium fluoride-rich solid electrolyte interphase (SEI) between SSEs and lithium metal.
• Characterization of the SEI layer's composition and properties.
• Electrochemical testing of lithium metal batteries utilizing the modified SSEs.

Main Results:

• The LiF-rich SEI effectively suppressed lithium dendrite penetration into SSEs.
• Enhanced room temperature critical current density of Li3PS4 to over 2 mA cm-2.
• Improved Li plating/stripping Coulombic efficiency from 88% to over 98% for LiF-coated Li3PS4.
• Blocked side reactions between SSEs and Li due to LiF's low electronic conductivity and stability.

Conclusions:

• In situ formation of an electronic insulating LiF-rich SEI is an effective strategy to prevent lithium dendrites in SSEs.
• This approach represents a significant advancement toward practical solid-state lithium metal batteries.
• The developed method enhances the safety and performance of next-generation high-energy batteries.