Solvent selection criteria for temperature-resilient lithium-sulfur batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Rechargeable lithium batteries face challenges in achieving both all-climate operation and high energy density simultaneously.
• Developing stable electrolytes is crucial for enhancing battery performance and lifespan.

Purpose of the Study:

• To design a novel electrolyte system for rechargeable lithium batteries that operates effectively across a wide temperature range.
• To improve the energy density and stability of lithium-sulfur batteries.

Main Methods:

• Utilized monodentate dibutyl ether as the sole solvent in the electrolyte.
• Investigated the electrolyte's solvation structure and polysulfide solubility at a concentration of 2 mol L^-1.
• Fabricated and tested pouch cells with thin lithium metal anodes and high-loading sulfurized polyacrylonitrile cathodes.

Main Results:

• The electrolyte exhibited weak solvation, leading to an aggregate structure and low polysulfide solubility.
• Achieved high lithium metal Coulombic efficiencies (99.0% at 23°C, 98.2% at -40°C, 98.7% at 50°C) and suppressed dendrite growth.
• Pouch cells retained 87.5% capacity at -40°C and 115.9% at 50°C compared to room temperature performance.

Conclusions:

• The developed electrolyte system enables stable lithium metal battery operation from -40°C to 50°C.
• Solvent-based design criteria were established for wide-temperature-range lithium-sulfur pouch cells.
• This approach offers a promising pathway for next-generation high-energy-density batteries.