Highly Safe Electrolyte Enabled via Controllable Polysulfide Release and Efficient Conversion for Advanced...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional lithium-sulfur batteries face challenges including flammability, polysulfide shuttling, and lithium dendrite formation.
• These issues limit the practical application and safety of lithium-sulfur battery technology.

Purpose of the Study:

• To develop highly safe lithium-sulfur batteries by addressing critical safety and performance bottlenecks.
• To investigate the efficacy of a novel flame-retardant electrolyte and a functional nanoconductive separator.

Main Methods:

• Utilized a flame-retardant electrolyte composed of dimethoxyether and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether.
• Employed a nanoconductive carbon-coated cellulose nonwoven separator.
• Conducted electrochemical testing on Li/Li symmetrical cells and bare sulfur cathode-based lithium-sulfur batteries.

Main Results:

• The flame-retardant electrolyte demonstrated excellent flame retardancy and suppressed polysulfide solubility.
• Li/Li symmetrical cells exhibited exceptional cycling stability over 2500 hours with minimal overpotential.
• Lithium-sulfur batteries maintained 83.6% capacity after 200 cycles at 0.5 C and showed high capacity retention at high rates (4 C) and elevated temperatures (60 °C).
• High-loading sulfur cathodes achieved over 806 mAh g⁻¹ capacity after 56 cycles.

Conclusions:

• The combination of a flame-retardant electrolyte and a carbon-coated separator significantly enhances the safety and stability of lithium-sulfur batteries.
• This strategy offers a promising pathway for developing high-performance, safe lithium-sulfur batteries for diverse operating conditions.