Slidable and Highly Ionic Conductive Polymer Binder for High-Performance Si Anodes in Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Silicon anodes offer high energy density for next-generation lithium batteries.
• Challenges include low initial coulombic efficiency (ICE) and significant volume expansion during cycling.
• These issues hinder the practical application of silicon anodes.

Purpose of the Study:

• To develop a flexible polymer binder that enhances the performance of silicon anodes.
• To improve initial coulombic efficiency (ICE), cycling stability, and rate capability.
• To address the volume expansion challenge in silicon electrodes.

Main Methods:

• Synthesis of a slidable and highly ionic conductive flexible polymer binder with a specific single-ion structure (SSIP).
• Utilizing polyrotaxane as a dynamic crosslinker within the binder.
• Fabrication and electrochemical testing of silicon anodes using the developed SSIP binder.

Main Results:

• The SSIP binder demonstrated a high ICE of up to 92.0%.
• Silicon anodes achieved a discharge capacity of ≈1650 mAh g^-1 after 400 cycles at 0.5C.
• High ICE (87.5%) and areal capacity (5.9 mAh cm^-2) were maintained with ultra-high Si loading (3.84 mg cm^-2).

Conclusions:

• The SSIP binder effectively mitigates volume expansion and improves ionic conductivity.
• This binder enhances the long-term cycling stability and rate performance of silicon anodes.
• SSIP shows significant potential for practical application in high energy density silicon-based lithium batteries.