A Polyurea-Crosslinked Gel Polymer Electrolyte for Solvation and Interphase Regulation in Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Polyurea (PUR) electrolytes show promise for lithium metal batteries due to tunable properties and mechanical strength.
• However, challenges like poor solubility, uncontrolled polymerization, and unstable interfaces limit their practical application.

Purpose of the Study:

• To develop novel polyurea-based polymerizable monomers (DPN and MPN) for constructing flame-retardant gel polymer electrolytes (P-DPN and P-MPN).
• To address solubility, electrolyte leakage, and interfacial instability issues in lithium metal batteries.

Main Methods:

• In situ polymerization strategy to synthesize P-DPN and P-MPN electrolytes.
• Mechanistic investigations using coordination chemistry and electronic structure analysis.
• Electrochemical performance testing of symmetric and full lithium metal cells.

Main Results:

• The polyurea framework's carbonyl and -NH groups facilitate homogeneous lithium deposition and accelerate ion transport.
• A robust LiF/Li3N-rich solid electrolyte interphase (SEI) suppresses parasitic reactions and dendrite growth.
• Stable cycling (>2300 h) in Li||P-MPN||Li symmetric cells and high performance in full cells with various cathodes, even at -20°C.

Conclusions:

• The developed molecular design strategy for in situ polyurea electrolytes enhances lithium metal battery performance and safety.
• Understanding of solvation and interphase regulation is deepened for advanced battery applications.