Sulfonic Groups Originated Dual-Functional Interlayer for High Performance Lithium-Sulfur Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur batteries offer high energy density but suffer from polysulfide shuttle effects and rapid capacity decay.
• The shuttle effect, caused by polysulfide dissolution in electrolytes, severely limits practical applications of Li-S batteries.

Purpose of the Study:

• To develop an effective strategy to suppress the shuttle effect in lithium-sulfur batteries.
• To enhance the electrochemical performance, including cycling stability and specific capacity, of lithium-sulfur batteries.

Main Methods:

• Fabrication of a sulfonated reduced graphene oxide (SRGO) interlayer for battery separators.
• Utilizing Lewis acid-base theory and Density Functional Theory (DFT) calculations to investigate interactions between sulfonic groups and polysulfides.
• Experimental testing of prototype batteries with the SRGO interlayer to evaluate performance.

Main Results:

• The SRGO interlayer physically blocks polysulfide migration and chemically anchors them via sulfonic groups.
• DFT calculations confirm strong interactions between sulfonic groups and lithium polysulfides, enhancing battery performance.
• Prototype batteries demonstrated a high reversible discharge capacity (>1300 mAh g⁻¹) and excellent capacity retention (802 mAh g⁻¹ after 250 cycles at 0.5 C).
• The SRGO interlayer facilitated uniform sulfur distribution, improving active sulfur utilization and alleviating sulfur deposition.

Conclusions:

• The SRGO interlayer is a promising approach to mitigate the shuttle effect in lithium-sulfur batteries.
• The synergistic effect of physical blocking and chemical anchoring by sulfonic groups significantly improves battery performance.
• This interlayer design leads to enhanced cycling life, high specific capacity, and excellent rate capability in lithium-sulfur batteries.