A Flexible and Mechanical Robust All-Solid-State Polymer Electrolyte with Microphase Separated Structure for...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) offer safety and cost benefits but suffer from low ionic conductivity and limited electrochemical stability.
• High-performance "polymer-in-salt" electrolytes face mechanical fragility due to high lithium salt concentrations, hindering their use against lithium dendrites.

Purpose of the Study:

• To design a novel SPE with a nanoscopically phase-separated polymer matrix capable of withstanding high lithium salt concentrations.
• To achieve a simultaneous improvement in ionic conductivity and mechanical properties for advanced lithium-ion batteries.
• To investigate the Li+ solvation structure and its correlation with electrolyte performance.

Main Methods:

• Fabrication of a macroscopically homogeneous yet nanoscopically phase-separated polymer matrix.
• Characterization of ionic conductivity (1.02 × 10⁻³ S cm⁻¹ at 60 °C) and mechanical properties (7 MPa at room temperature).
• Analysis of Li+ solvation structure and ion cluster formation at phase interfaces.

Main Results:

• The designed SPE demonstrates high ionic conductivity and robust mechanical properties, suitable for high lithium salt concentrations.
• Formation of large ion clusters and selective lithium salt enrichment at phase interfaces were identified as key factors.
• Achieved a critical current density (CCD) of 2.2 mA cm⁻².

Conclusions:

• A promising strategy for developing mechanically robust SPEs with high ionic conductivity through microstructure control.
• The nanoscopically phase-separated polymer matrix enables high salt loading without compromising mechanical integrity.
• This approach offers a pathway for optimizing SPEs for demanding battery applications.