Rational electrolyte solvent screening for high-energy lithium metal batteries at low temperatures

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Weakening solvation ability in electrolytes is key for lithium-metal battery performance.
• Challenges include sluggish kinetics and lithium dendrite formation, especially at low temperatures.

Purpose of the Study:

• To propose a guideline for rational electrolyte solvent screening.
• To identify descriptors for quantifying solvation effects and optimizing solvent properties.

Main Methods:

• Utilized restrained electrostatic potential of coordinated oxygen as a descriptor.
• Incorporated dipole moment as a correction descriptor for electric field sensitivity and interphase stability.
• Designed and screened asymmetric fluorinated ethers as electrolyte solvents.

Main Results:

• Identified 3,3,3-trifluoropropyl-1-methyl ether as an optimal solvent.
• Demonstrated stable lithium plating/stripping with promoted kinetics and reversibility from 30 to -60°C.
• Achieved over 90% capacity retention after 200 cycles in Li|LCO coin cells and high specific energy in pouch cells at -40°C.

Conclusions:

• The proposed screening guideline enables rational design of high-performance electrolyte solvents.
• The new electrolyte solvent significantly enhances lithium-metal battery performance and stability across a wide temperature range.
• This work paves the way for practical, high-energy-density lithium-metal batteries operating at low temperatures.