Synergistic Cathode-Electrolyte Engineering for Enhanced Longevity in Li-S Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries face challenges with ultra-high sulfur loading, including the shuttle effect and uneven lithium deposition, hindering long-cycle performance.
• The shuttle effect involves polysulfide migration, leading to capacity fading and reduced battery lifespan.
• Lithium dendrite growth under high current conditions compromises battery safety and stability.

Purpose of the Study:

• To develop a novel cathode host material to mitigate the shuttle effect in Li-S batteries.
• To enhance the long-cycle performance of ultra-high sulfur loading Li-S batteries.
• To suppress lithium dendrite growth for improved battery safety and stability.

Main Methods:

• Preparation of a novel MBene-based composite material using ultrasonic freeze etching as a cathode host.
• Introduction of sodium selenite (Na2SeO3) into the electrolyte to suppress lithium dendrite growth via the reverse tip effect.
• Electrochemical testing of the designed Li-S cells with ultra-high sulfur loading.

Main Results:

• The MBene-based cathode host effectively inhibited the shuttle effect due to its unique structure and active sites.
• The addition of Na2SeO3 suppressed lithium dendrite growth through preferential sodium ion deposition.
• The optimized Li-S cell achieved an initial capacity of 778.2 mAh g⁻¹, with 93.6% capacity retention over 850 cycles at a high sulfur loading of 10.62 mg cm⁻².

Conclusions:

• The synergistic strategy of optimizing both cathode and electrolyte systems is highly effective for ultra-high sulfur loading Li-S batteries.
• This approach significantly enhances cycle stability and mitigates key degradation mechanisms.
• The findings offer a promising pathway for developing next-generation high-energy-density Li-S batteries.