Surface nitridation of Si enabled gradient artificial solid electrolyte interface and self-optimized structural...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Silicon (Si) anodes offer high capacity for lithium-ion batteries but suffer from volume expansion and capacity fading.
• The formation of a solid electrolyte interphase (SEI) on silicon anodes is crucial for battery performance but often leads to instability.
• Existing methods struggle to control SEI growth and manage silicon's structural changes during cycling.

Purpose of the Study:

• To mitigate capacity fading in silicon anodes for lithium-ion batteries.
• To introduce a stable, artificial SEI layer on micron-sized silicon particles.
• To investigate the self-optimized structural evolution of silicon anodes.

Main Methods:

• Coating micron-sized silicon particles with a silicon nitride (SiNx) layer.
• In-situ conversion of the SiNx layer into a lithium-silicon-nitride (LixSiny) based artificial SEI.
• Characterization of the electrode structure and electrochemical performance.

Main Results:

• The artificial SEI effectively restricted SEI growth to the outer surface.
• A self-optimized nanoporous silicon network formed within 20 cycles.
• The nanoporous structure exhibited reduced volume expansion and enhanced reaction kinetics.
• The Si@SiNx/TiN composite demonstrated high capacity, stable cycling, and excellent fast-charging performance.

Conclusions:

• The SiNx surface layer successfully creates a stable artificial SEI, addressing capacity fading in silicon anodes.
• The induced self-optimized nanoporous silicon structure enhances electrochemical performance and cycling stability.
• This approach presents a promising strategy for developing high-performance silicon anodes for advanced lithium-ion batteries.