Minimizing Polysulfide Shuttle Effect in Lithium-Ion Sulfur Batteries by Anode Surface Passivation

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur batteries offer high theoretical energy density but suffer from polysulfide shuttle reactions on nonmetal anodes.
• These reactions lead to low Coulombic efficiency and capacity degradation, limiting practical applications.
• Graphite and silicon anodes are susceptible to these detrimental side reactions.

Purpose of the Study:

• To suppress polysulfide shuttle reactions in lithium-sulfur batteries using nonmetal anodes.
• To improve the Coulombic efficiency and long-term cycling stability of sulfur cathodes.
• To enhance the overall performance of graphite-sulfur batteries through surface passivation.

Main Methods:

• Coating graphite anodes with aluminum oxide (Al2O3) layers using atomic layer deposition (ALD).
• Optimizing the Al2O3 layer thickness to 2 nm for effective passivation.
• Electrochemical testing to evaluate Coulombic efficiency, discharge capacity, and cycling stability.

Main Results:

• A 2 nm Al2O3 coating on the graphite anode improved first-cycle Coulombic efficiency from 84% to 96%.
• Subsequent cycle Coulombic efficiency increased from 94% to 97% with the Al2O3 passivation layer.
• Discharge capacity at the 100th cycle rose to 550 mAh g⁻¹ from 440 mAh g⁻¹ compared to pristine graphite anodes.

Conclusions:

• Al2O3 passivation effectively minimizes the formation of insoluble sulfides (Li2S2, Li2S) on the graphite anode surface.
• This surface passivation strategy significantly enhances the efficiency and capacity retention of graphite-sulfur batteries.
• The method is applicable to other sulfur-based battery systems with various anodes (Li, Si, Sn) for high-performance energy storage.