A conjugated conductive polymer coating towards a robust micro-Si anode for lithium storage

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Silicon (Si) anodes offer high theoretical capacity for lithium-ion batteries but suffer from poor cycling stability due to large volume expansion.
• Developing protective coatings is crucial to mitigate Si particle pulverization and maintain electrode integrity during cycling.

Purpose of the Study:

• To design and fabricate a robust, conductive dual-layered coating for micro-sized Si particles.
• To investigate the impact of the coating on the solid electrolyte interphase (SEI) formation and electrochemical performance.
• To demonstrate stable lithium storage in high-rate battery applications.

Main Methods:

• Utilizing the cyclization chemistry of polyacrylonitrile to form a conjugated polymer sheath.
• Applying the polymer sheath over amorphous carbon-coated micro-sized Si particles to create a dual-layered structure.
• Electrochemical testing of the coated Si anodes in lithium-ion cells.

Main Results:

• A robust and conductive conjugated polymer sheath was successfully constructed over Si particles.
• The dual-layered coating design significantly improved the stability and conductivity of the Si anode.
• The coating guided the formation of a lithium fluoride (LiF)-rich solid electrolyte interphase (SEI).
• The coated Si anodes demonstrated stable lithium storage for 400 cycles at a high rate.

Conclusions:

• The polyacrylonitrile-derived conjugated polymer coating effectively protects Si anodes.
• The dual-layer design and LiF-rich SEI are key to achieving stable, high-rate lithium storage.
• This approach offers a promising strategy for developing advanced Si-based lithium-ion battery anodes.