10 μm-Thick High-Strength Solid Polymer Electrolytes with Excellent Interface Compatibility for Flexible...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid polymer electrolytes (SPEs) are crucial for developing safer all-solid-state lithium-metal batteries.
• Achieving thin, mechanically robust, and highly conductive SPEs remains a significant challenge.

Purpose of the Study:

• To develop an ultrathin, mechanically strong, and highly conductive solid polymer electrolyte.
• To enhance interface compatibility between electrolytes and electrodes in lithium-metal batteries.

Main Methods:

• Fabrication of a 10 μm-thick SPE using modified polyethylene as the host, incorporating poly(ethylene glycol) methyl ether acrylate and lithium salts.
• Incorporation of porous poly(methyl methacrylate)-polystyrene interface layers to improve electrolyte-electrode compatibility.
• Electrochemical performance evaluation using Li//Li symmetric cells and LiFePO4//Li and LiCoO2//Li pouch cells.

Main Results:

• The SPE achieved an ultrahigh ionic conductance of 34.84 mS at room temperature and excellent mechanical properties (103.0 MPa strength, 142.3% elongation).
• The Li//Li symmetric cell demonstrated stable cycling for over 1500 hours at 60 °C.
• LiFePO4//Li pouch cells showed stable cycling over 1000 cycles at 1 C with 76.4% capacity retention at 60 °C.

Conclusions:

• The developed ultrathin SPE offers a promising strategy for high-performance, safe, and flexible all-solid-state lithium-metal batteries.
• The enhanced interface compatibility and mechanical properties contribute to the superior electrochemical stability.
• The material's flexibility and safety characteristics are validated through mechanical stress tests.