Electrolyte Design for Improving Mechanical Stability of Solid Electrolyte Interphase in Lithium-Sulfur Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Practical lithium-sulfur (Li-S) batteries face challenges due to unstable solid electrolyte interphase (SEI) formation in conventional ether electrolytes.
• This instability leads to rapid capacity degradation and limited cycle life.

Purpose of the Study:

• To propose a novel electrolyte system for Li-S batteries that enhances SEI stability and mechanical integrity.
• To improve the overall performance and longevity of Li-S batteries through advanced electrolyte design.

Main Methods:

• Investigated a co-solvent electrolyte system comprising 1,3,5-trioxane (TO) and 1,2-dimethoxyethane (DME).
• Analyzed the composition and mechanical properties of the SEI formed in the TO-DME electrolyte.
• Evaluated the electrochemical performance, including cycle life and capacity retention, of Li-S cells using the developed electrolyte.

Main Results:

• The TO-DME electrolyte facilitated the formation of a high-mechanical-stability, organic-rich SEI.
• This robust SEI effectively mitigated SEI cracking and regeneration, reducing the consumption of lithium, polysulfides, and electrolytes.
• Li-S batteries with the TO-based electrolyte demonstrated an extended lifespan from 75 to 216 cycles.
• A 417 Wh/kg Li-S pouch cell successfully completed 20 cycles.

Conclusions:

• The proposed TO-DME electrolyte system offers a promising strategy for constructing stable SEI layers in Li-S batteries.
• This electrolyte design significantly enhances the cycle life and stability of Li-S batteries, paving the way for their practical implementation.
• The study presents a new direction for electrolyte engineering in next-generation high-energy-density batteries.