Ultra-thin solid electrolyte interphase evolution and wrinkling processes in molybdenum disulfide-based lithium-ion...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Molybdenum disulfide (MoS2) is a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity.
• A major challenge for MoS2 anodes is the instability of the solid electrolyte interphase (SEI), which degrades battery performance.
• Understanding the SEI formation and MoS2 structural evolution during cycling is critical for developing robust LIBs.

Purpose of the Study:

• To investigate the interfacial processes, including SEI formation and lithiation/delithiation, on monolayer MoS2.
• To elucidate the protective role of fluoroethylene carbonate (FEC) as an additive in stabilizing the MoS2 anode.
• To establish structure-reactivity correlations for MoS2-based LIBs.

Main Methods:

• In situ atomic force microscopy (AFM) was employed to monitor interfacial phenomena in real-time.
• Ultra-flat monolayer MoS2 was used as the anode material.
• Fluoroethylene carbonate (FEC) was utilized as an electrolyte additive.

Main Results:

• The use of FEC additive induced the formation of ultra-thin and dense SEI films, effectively protecting the MoS2 anode.
• The evolution and quantitative analysis of the FEC-derived SEI film during battery cycling were performed.
• The formation of wrinkle-structure networks during the lithiation process was detailed, revealing structure-reactivity relationships.

Conclusions:

• Fluoroethylene carbonate significantly enhances the stability of molybdenum disulfide anodes in lithium-ion batteries by forming a protective SEI layer.
• The study provides a detailed understanding of the interfacial mechanisms and structural evolution of MoS2 during electrochemical cycling.
• These findings offer crucial insights for designing high-performance and durable MoS2-based LIBs.