Dry-Processable Polymer Electrolytes for Solid Manufactured Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid-state batteries require electrolytes with fast ion transport, good interfacial compatibility, and mechanical strength.
• Current solid-state electrolytes face challenges in meeting these combined operating requirements.

Purpose of the Study:

• To develop a novel solid polymer electrolyte (SPE) with a 3D network structure.
• To enhance ionic conductivity and mechanical stability for solid-state battery applications.

Main Methods:

• A 3D network SPE was synthesized using in situ graft polymerization of cellulose nanocrystals (CNCs) and polyacrylonitrile (PAN).
• A dry-processing method was employed, utilizing minimal solvent.
• The SPE was characterized for ionic conductivity, mechanical properties, and interfacial compatibility.

Main Results:

• The developed SPE exhibits a 3D network structure with excellent mechanical stability (9.5 MPa tensile strength) and low density (1.2 g cm^-3).
• High ionic conductivity of 3.9 × 10^-4 S cm^-1 at 18 °C and a high lithium ion migration number (t_Li = 0.8) were achieved.
• Efficient Li⁺ transport pathways were facilitated by functional groups on CNCs and dipole-dipole interactions between CNCs and PAN.

Conclusions:

• The combination of hard CNCs and soft PAN in a 3D network provides a promising strategy for high-performance solid polymer electrolytes.
• The developed SPE demonstrates potential for use in solid-state batteries due to its enhanced ionic conductivity and mechanical properties.
• A tightly formed interface with LiFePO₄ cathodes was achieved, further improving battery performance.