Strategy for High-Energy Li-S Battery Coupling with a Li Metal Anode and a Sulfurized Polyacrylonitrile Cathode

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density.
• Polysulfide formation and shuttling are key challenges in Li-S battery performance.
• Carbonate electrolytes are typically avoided in Li-S batteries due to poor Li metal anode compatibility.

Purpose of the Study:

• To design and investigate a novel carbonate-based electrolyte for Li-S batteries.
• To improve the stability of Li metal anodes and sulfurized polyacrylonitrile (SPAN) cathodes.
• To overcome the limitations of traditional ether-based electrolytes in Li-S systems.

Main Methods:

• Formulation of a specific carbonate-based electrolyte (0.8 M LiTFSI, 0.2 M LiDFOB, 0.05 M LiPF6 in EMC/FEC).
• Electrochemical testing of Li-S cells with Li metal anode and SPAN cathode.
• Operando optical microscopy, atomic force microscopy (AFM), and Raman spectroscopy to analyze electrode behavior.

Main Results:

• The developed electrolyte effectively stabilizes both Li metal anodes and SPAN cathodes.
• High Coulombic efficiencies (>99.9%) and stable cyclability were achieved.
• Operando microscopy confirmed dense, uniform Li deposition and suppressed dendrite growth.
• Operando Raman spectroscopy revealed reversible Li+ storage via disulfide bond dynamics in SPAN.

Conclusions:

• The designed carbonate-based electrolyte enables high-performance Li-S batteries.
• This electrolyte strategy effectively addresses Li anode instability and SPAN cathode issues.
• The battery demonstrated 73.5% capacity retention over 1000 cycles, highlighting its potential for practical applications.