In Situ Solid Conversion into Mechanically Adaptive LiF-Rich Solid Electrolyte Interphase via MgF₂ Precursor on Si...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Silicon anodes offer high capacity for lithium-ion batteries (LIBs) but suffer from volume expansion and unstable solid electrolyte interphase (SEI).
• Conventional SEI layers are mechanically weak and have poor ionic conductivity, limiting battery lifespan.
• Developing stable anodes is crucial for advancing high-energy-density LIBs.

Purpose of the Study:

• To engineer a stable interface for silicon anodes using an in situ converted MgF2 layer.
• To enhance the ionic conductivity, electronic insulation, and mechanical properties of the SEI layer.
• To improve the overall performance and durability of silicon-based LIBs.

Main Methods:

• Decorating silicon nanoparticles with a magnesium fluoride (MgF2) layer.
• Investigating the in situ conversion of MgF2 into a LiF-rich SEI during lithiation.
• Electrochemical testing of Si@MgF2-1 anodes in half-cell and full-cell configurations.

Main Results:

• The MgF2 layer converts in situ to form a robust SEI with 94.2% coating integrity.
• Si@MgF2-1 anodes exhibit high initial coulombic efficiency (91.7%) and excellent rate capability (2000 mAh g⁻¹ at 10 C).
• Remarkable cycling stability was achieved, retaining 1794.9 mAh g⁻¹ after 500 cycles.

Conclusions:

• The MgF2 conversion strategy effectively creates a mechanically adaptive, LiF-rich SEI layer.
• This approach significantly enhances the stability and performance of silicon anodes for LIBs.
• The findings pave the way for durable and high-performance silicon-based batteries.