Integrating SEI into Layered Conductive Polymer Coatings for Ultrastable Silicon Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Silicon anodes offer high theoretical capacity but suffer from significant volume expansion during cycling.
• This expansion leads to unstable solid electrolyte interphase (SEI) formation and rapid capacity decay in lithium-ion batteries.
• Developing strategies to stabilize the SEI is critical for high-performance silicon anodes.

Purpose of the Study:

• To engineer a stable SEI on silicon nanoparticles using a novel coating.
• To improve the cycling stability and rate capability of silicon anodes.
• To demonstrate the potential of polymer-directed SEI formation for advanced battery anodes.

Main Methods:

• Synthesized silicon nanoparticles coated with a layered conductive polyaniline (LCP).
• Investigated the in situ formation of an LCP-integrated hybrid SEI.
• Evaluated the electrochemical performance, including cycling stability and rate capability, of the modified silicon anodes.

Main Results:

• The conformal LCP coating facilitated the formation of a uniform, flexible hybrid SEI with integrated organic and inorganic components.
• The engineered SEI effectively buffered silicon's volume changes and maintained homogeneous ion transport.
• Silicon anodes achieved high areal capacity (≈3 mAh cm⁻²) with remarkable cycling stability over 150 cycles and good rate performance (942 mAh g⁻¹ at 5 A g⁻¹).

Conclusions:

• Layered conductive polyaniline coating is a promising strategy for stabilizing silicon anodes.
• Regulating SEI properties through polymer-directed formation enhances mechanical and electrochemical stability.
• This approach holds significant potential for developing next-generation high-energy-density batteries.