Beyond Polymerization: In Situ Coupled Fluorination Enables More Stable Interfaces for Solid-State Lithium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• In situ polymerization improves physical interfacial stability in solid-state batteries.
• Electrochemical degradation of polymerized interfaces, especially at high voltages, is a critical challenge.
• Interphase engineering is crucial for polymerization and polymer stability.

Purpose of the Study:

• To develop a novel strategy for creating durable solid-state battery interfaces.
• To enhance both physical and electrochemical stability of polymerized interfaces.
• To overcome the limitations of current in situ polymerization methods for high-voltage applications.

Main Methods:

• Pioneered an in situ polymerization-fluorination (Poly-FR) strategy.
• Designed a bifunctional initiator for polymerization and on-surface lithium donor reactions.
• Integrated in situ fluorination to convert surface impurities (Li2CO3) into LiF-rich interphases.

Main Results:

• The Poly-FR strategy created durable interfaces with excellent physical and electrochemical stabilities.
• In situ fluorination effectively inhibited aggressive (de)lithiation intermediates and protected against chemical degradation.
• Poly-FR mediated symmetric Li|Li cells achieved 12,000 h cycling stability.
• Solid-state cells (NCM811 cathodes, Li metal anodes) showed 400 cycles with 83.4% retention at 4.5 V.

Conclusions:

• The Poly-FR strategy significantly surpasses the stability limitations of polymerization alone.
• This approach enables ultrastable cycling performance in solid-state batteries at high voltages.
• The findings point toward advanced in situ polymerization techniques for next-generation batteries.