Surface-localized phase mediation accelerates quasi-solid-state reaction kinetics in sulfur batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but suffer from poor cycle stability.
• Uncontrolled dissolution of polysulfides in the electrolyte leads to capacity fading and low coulombic efficiency.
• Existing strategies like quasi-solid-state reactions improve stability but compromise reaction kinetics.

Purpose of the Study:

• To address the stability and kinetic limitations in Li-S batteries.
• To propose a novel surface-localized polysulfide-solvation strategy.
• To enhance reaction pathways and kinetics through rational electrolyte design.

Main Methods:

• Utilizing an organic phase mediator with a weakly solvating electrolyte.
• Implementing a surface-localized approach to complex and mediate surface polysulfides.
• Globally restricting polysulfide dissolution while promoting surface solvation.

Main Results:

• Achieved excellent rate performance with 494 mAh g^-1_sulfur at 16 C.
• Demonstrated stabilized cycling over 300 cycles with 90.2% capacity retention.
• Enabled steady operation of a 2.4 Ah pouch cell with 331 Wh kg^-1 energy density.

Conclusions:

• The surface-localized phase mediation strategy effectively controls electrode reaction pathways and kinetics.
• This approach enhances Li-S battery performance by managing polysulfide behavior.
• Rational electrolyte design is crucial for advancing Li-S battery technology.