Locally Concentrated Ionic Liquid Electrolytes Enabling Low-Temperature Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium metal anodes are crucial for high-energy-density batteries.
• Challenges include low Coulombic efficiency and dendrite formation at low temperatures.
• Existing electrolytes struggle to maintain performance below 0°C.

Purpose of the Study:

• To develop a novel electrolyte for low-temperature lithium metal batteries.
• To address dendrite growth and improve Coulombic efficiency at sub-zero temperatures.
• To demonstrate the viability of lithium metal batteries in cold environments.

Main Methods:

• A poorly-flammable, locally concentrated ionic liquid electrolyte was synthesized.
• The electrolyte's stability and ionic solvation structure at low temperatures were analyzed.
• Electrochemical performance, including Coulombic efficiency and cycling stability, was evaluated at -20°C.

Main Results:

• The proposed electrolyte maintained its structure and enabled dendrite-free lithium metal anode operation at -20°C.
• A Coulombic efficiency of 98.9% was achieved at 0.5 mA cm⁻².
• Lithium metal batteries demonstrated 70% capacity retention after 100 cycles at -20°C.

Conclusions:

• Locally concentrated ionic liquid electrolytes are effective for low-temperature lithium metal batteries.
• The developed electrolyte overcomes key limitations of current battery technology for cold conditions.
• This work paves the way for reliable energy storage in sub-zero environments.