Universal Copolymerization of Crosslinked Polyether Electrolytes for All-Solid-State Lithium-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) are crucial for all-solid-state batteries.
• Poly(1,3-dioxane) (PDOL) electrolytes offer high conductivity but suffer from crystallization and residual monomers.
• Existing PDOL electrolytes require improved stability and processing.

Purpose of the Study:

• To develop high-performance PDOL electrolytes using a universal copolymerization strategy.
• To address crystallization and residual monomer issues in PDOL-based SPEs.
• To enhance the thermo-mechanical stability and ionic conductivity of PDOL electrolytes.

Main Methods:

• A copolymerization strategy integrating LiTFSI and LiDFOB with epoxy crosslinkers was employed.
• In situ polymerization methods were utilized for electrolyte synthesis.
• Characterization of thermo-mechanical stability, ion migration, electrochemical window, and ionic conductivity was performed.

Main Results:

• The crosslinked PDOL electrolyte exhibited excellent thermo-mechanical stability up to 100 °C.
• A high ion migration number (t_Li+ = 0.42) and a wide electrochemical window (≈5.0 V vs Li⁺/Li) were achieved.
• High ionic conductivity (4.5×10^-4 S cm^-1) and robust performance in solid-state lithium metal batteries were demonstrated with minimal residual monomers and no crystallization.

Conclusions:

• The proposed copolymerization strategy effectively creates stable, high-performance PDOL electrolytes.
• This approach overcomes key limitations of previous PDOL electrolytes, enabling practical applications.
• The developed electrolytes show significant promise for advanced all-solid-state lithium metal batteries.