The Manipulation of Ring-Open Polymerization Process to Boost the Electrochemical Performance for Solid-State Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state polyether electrolytes offer high conductivity and interfacial compatibility for lithium batteries.
• Controlling ring-opening polymerization (ROP) of 1,3-dioxolane (DOL) is challenging, leading to high molecular weight and crystallinity in poly(1,3-dioxolane) (PDOL).
• These properties impede Li+ diffusion and degrade interfacial contact in solid-state lithium batteries.

Purpose of the Study:

• To regulate the ROP of DOL and improve the properties of PDOL electrolytes.
• To enhance the performance of solid-state lithium metal batteries by optimizing electrolyte composition.

Main Methods:

• Introduced trimethylsilyl isocyanate (IPTS) as a moisture-eliminating agent into the DOL ROP system.
• Weakened the Li salt-based initiating system to control polymerization.
• Fabricated and tested solid-state electrolytes with varying IPTS content (e.g., 3 wt.%).

Main Results:

• PDOL electrolytes with 3 wt.% IPTS achieved an ionic conductivity of 2.8×10⁻⁴ S/cm and a high Li+ transference number (0.68).
• The modified electrolytes demonstrated excellent stability with Li anodes, enabling stable cycling for over 1100 hours.
• LiFePO₄|PDOL-3%IPTS|Li cells showed significantly improved capacity retention (89.2% after 200 cycles at 25°C) compared to unmodified PDOL (6.6% after 70 cycles).

Conclusions:

• Trimethylsilyl isocyanate effectively regulates DOL ROP, yielding PDOL electrolytes with enhanced ionic conductivity and stability.
• The optimized PDOL electrolytes significantly improve the cycling performance and capacity retention of solid-state lithium metal batteries.
• This approach provides a viable strategy for developing high-performance solid-state electrolytes for next-generation lithium batteries.