Sulfurized Polyacrylonitrile Cathodes With Rapid Redox Kinetics for High-Capacity and Long-Cycle-Life Lithium-Sulfur...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sulfurized polyacrylonitrile (SPAN) shows promise for lithium-sulfur (Li-S) batteries by mitigating the polysulfide shuttle.
• Challenges remain in SPAN cathode implementation due to solvation-induced structural changes and slow redox kinetics in ether electrolytes.

Purpose of the Study:

• To develop a hierarchically structured composite (HSPAN) for improved Li-S battery performance.
• To address the limitations of SPAN cathodes in ether-based electrolytes.

Main Methods:

• Fabrication of HSPAN via pyrolytic transformation of polystyrene templates and carbon nanotubes (CNTs) integration.
• Electrochemical characterization of HSPAN cathodes in Li-S batteries.
• Density functional theory (DFT) calculations to analyze electronic structure and redox activity.

Main Results:

• HSPAN architecture provides dual electron-ion transport channels, enhancing sulfur redox kinetics.
• Suppression of short-chain sulfur dissolution and stable cycling achieved in ether electrolytes.
• Optimized HSPAN cathode delivered 1145 mAh g⁻¹ at 1 C with 82% capacity retention over 800 cycles.
• DFT calculations confirmed narrowed HOMO-LUMO gap and enhanced conductivity/redox activity of sulfurized polyacrylonitrile.

Conclusions:

• The engineered HSPAN composite offers a viable pathway for high-energy-density Li-S batteries.
• Fundamental insights into solvation dynamics of sulfurized polymers were provided.
• Rational electrode engineering is crucial for advancing Li-S battery technology.