A Polymer Network Layer Containing Dually Anchored Ionic Liquids for Stable Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high energy density potential for next-generation energy storage.
• The polysulfide shuttle effect remains a major challenge, hindering the stability and efficiency of Li-S batteries.
• Existing solutions often introduce free ions, complicating the electrolyte system.

Purpose of the Study:

• To develop a novel electrolyte additive for enhancing the cycling performance and coulombic efficiency of Li-S batteries.
• To address the polysulfide shuttle problem without introducing free ionic species.
• To improve lithium-ion transport while preventing polysulfide migration.

Main Methods:

• Development of a unique polymer network containing dually anchored ionic liquids (DA-PIL).
• Functionalization of a polypropylene separator with the DA-PIL layer.
• Electrochemical testing of Li-S cells with the functionalized separator, including long-term cycling and capacity measurements.

Main Results:

• The DA-PIL layer effectively suppresses polysulfide shuttling by creating an ionic function layer with amphiphilic properties.
• Fast lithium transportation is facilitated through cooperative electrostatic interactions within the DA-PIL network.
• Li-S batteries with the DA-PIL functionalized separator demonstrated over 1600 hours of stable cycling at 0.25 mA cm⁻², with a high initial discharge capacity of 827.4 mAh g⁻¹ and retention of 630.6 mAh g⁻¹ after 1000 cycles.

Conclusions:

• The DA-PIL network provides a 'clean' electrolyte additive strategy for highly stable and efficient Li-S batteries.
• This approach overcomes the polysulfide shuttle issue and enhances lithium-ion conductivity.
• The developed DA-PIL functionalized separator shows significant promise for advancing high-energy-density Li-S battery technology.