A highly concentrated phosphate-based electrolyte for high-safety rechargeable lithium batteries

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Developing safe and efficient electrolytes is crucial for advancing lithium metal batteries.
• Current electrolytes face challenges with flammability and lithium dendrite formation, hindering battery performance and safety.
• Phosphate-based electrolytes offer potential for nonflammable solutions.

Purpose of the Study:

• To develop a totally nonflammable phosphate-based electrolyte for enhanced lithium metal battery safety.
• To investigate the properties and performance of a highly concentrated LiFSI/TMP electrolyte.
• To assess the electrolyte's compatibility with battery components and its effect on lithium dendrite suppression.

Main Methods:

• Preparation of a concentrated electrolyte solution: 5 mol L-1 Li bis(fluorosulfonyl) imide (LiFSI) in trimethyl phosphate (TMP).
• Electrochemical compatibility testing with graphite and aluminum (Al) current collectors.
• Analysis of the solid electrolyte interphase (SEI) layer formed on the lithium metal anode.
• Evaluation of lithium dendrite suppression using the developed electrolyte.

Main Results:

• A nonflammable phosphate-based electrolyte (5 M LiFSI/TMP) was successfully prepared.
• The electrolyte demonstrated excellent compatibility with graphite and showed no aluminum corrosion.
• A stable, lithium fluoride (LiF)-rich SEI layer was formed, effectively suppressing lithium dendrite growth.
• The concentrated electrolyte significantly enhances the safety of lithium metal batteries.

Conclusions:

• The 5 M LiFSI/TMP electrolyte is a promising candidate for safe and high-performance lithium metal batteries.
• The nonflammable nature and dendrite suppression capabilities address key safety concerns.
• This work contributes to the development of next-generation energy storage solutions.