Confining Hyperbranched Star Poly(ethylene oxide)-Based Polymer into a 3D Interpenetrating Network for a...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Traditional poly(ethylene oxide)-based polymer electrolytes suffer from low ionic conductivity and poor mechanical properties, limiting their use in all-solid-state lithium-ion batteries (LIBs).
• Developing solid polymer electrolytes with enhanced ionic conductivity, mechanical strength, and electrochemical stability is crucial for advancing safer and higher-performance LIBs.

Purpose of the Study:

• To design and synthesize a novel hyperbranched star polymer electrolyte with a unique rigid-flexible coupling network.
• To improve the ionic conductivity, mechanical properties, and electrochemical stability of polymer electrolytes for LIB applications.

Main Methods:

• Fabrication of a 3D interpenetrating cross-linking network using UV-photopolymerization of ethoxylated trimethylolpropane triacrylate with a hyperbranched star polymer containing poly(ethylene glycol) methyl ether methacrylate segments.
• Incorporation of lithium salt into the polymer network.
• Characterization of ionic conductivity, electrochemical stability window, mechanical properties, and lithium dendrite suppression capabilities.
• Testing of the assembled LiFePO4//Li battery performance.

Main Results:

• The developed solid polymer electrolyte exhibits enhanced ionic conductivity (6.8 × 10^-5 S cm^-1 at 50 °C) and a wide electrochemical stability window (5.1 V vs Li/Li⁺).
• The rigid 3D network provides excellent mechanical stability, effectively suppressing lithium dendrite growth, enabling stable operation of Li symmetrical cells for 1000 hours at 0.05 and 0.1 mA cm^-2.
• The LiFePO4//Li cells assembled with this electrolyte demonstrated good cycle performance at 50 °C.

Conclusions:

• The hyperbranched star polymer electrolyte with a nanoconfined cross-linking structure offers a promising solution for high-safety and high-performance all-solid-state LIBs.
• The rigid-flexible coupling network design effectively enhances both ionic conductivity and mechanical integrity.
• This material demonstrates significant potential for practical application in advanced lithium-ion battery technology.