Tailoring Lithium Polysulfide Coordination and Clustering Behavior through Cationic Electrostatic Competition.

Area of Science:

• Materials Chemistry
• Electrochemistry
• Battery Technology

Background:

• Lithium-sulfur (Li-S) batteries rely on soluble lithium polysulfide intermediates.
• Polysulfide solvation and aggregation impact Li-S battery efficiency and reversibility.
• Aggregation is problematic, especially at low temperatures and lean electrolyte conditions.

Purpose of the Study:

• To investigate the influence of cationic species on polysulfide aggregation.
• To understand how competing cation-anion interactions affect polysulfide coordination.
• To improve Li-S battery performance under challenging conditions.

Main Methods:

• Investigated the effect of ammonium trifluoroacetate additive in Li-S battery electrolytes.
• Studied polysulfide coordination shell modification by cations.
• Evaluated electrochemical conversion kinetics under lean electrolyte and subzero conditions.

Main Results:

• Ammonium cations (NH4+) were found to positively tailor the polysulfide coordination shell.
• Introduction of NH4+ cations hindered polysulfide cluster formation.
• Improved electrochemical conversion kinetics were observed under challenging conditions.

Conclusions:

• Cationic species can compete with S_x^2- dianions, preventing polysulfide aggregation.
• Ammonium additives enhance Li-S battery performance in lean electrolytes and at low temperatures.
• This work provides a more comprehensive understanding of polysulfide coordination chemistry in Li-S batteries.