Anion Coordination Transition Enabled by Ion-Dipole Interactions At Low Temperatures

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Improving low-temperature (LT) electrolyte performance is crucial for advanced batteries.
• Conventional methods focusing on Li+-solvent interactions face challenges like poor anion coordination and interfacial issues.

Purpose of the Study:

• To develop a "polarity-contrast" electrolyte design strategy for stable LT operation.
• To engineer anion-solvent interactions for enhanced LT electrolyte performance.

Main Methods:

• Selected solvent pairs (dimethoxymethane/fluoroethylene carbonate) with contrasting electrostatic potentials.
• Investigated anion-solvent interactions and solvation structure formation at LT.
• Fabricated and tested Li||SPAN full cells and Li||SPAN pouch cells under LT conditions.

Main Results:

• Achieved a stable, anion-rich solvation structure at LT.
• Facilitated the formation of a fluorine-rich solid electrolyte interphase.
• Demonstrated excellent LT performance in Li||SPAN cells, including high capacity and cycling stability at -40 °C and -20 °C.

Conclusions:

• The "polarity-contrast" strategy effectively regulates anion-solvent interactions for LT stability.
• This approach enables uniform lithium deposition and superior performance in LT lithium-ion batteries.
• The developed electrolytes show promise for practical applications requiring reliable operation at low temperatures.