Geminal Dicationic Ionic Liquid-Based Freestanding Ion Membrane for High-Safety Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Developing advanced ion membranes is crucial for high-performance energy storage solutions.
• Freestanding ion membranes require high ionic conductivity, electrochemical stability, mechanical strength, and safety.

Purpose of the Study:

• To synthesize and fabricate a novel geminal dicationic ionic liquid (GDIL)-based flexible ion conductive material (iMembrane).
• To evaluate the electrochemical performance, thermal stability, and safety characteristics of the iMembrane for lithium battery applications.

Main Methods:

• Fabrication of a freestanding ion membrane (iMembrane) using geminal dicationic ionic liquids (GDILs).
• Electrochemical testing, including lithium-ion intercalation/de-intercalation at the iMembrane/graphite interface.
• Compatibility assessment with lithium metal anodes and LiFePO4 cathodes.
• Safety testing of assembled soft-packed batteries via nail penetration.

Main Results:

• The iMembrane exhibited high thermal stability, broad electrochemical stability, and capable ionic conductivity.
• Stable lithium-ion intercalation/de-intercalation occurred without imidazole ring co-intercalation, due to a specific anion-derived solid electrolyte interphase.
• The iMembrane demonstrated excellent compatibility with lithium metal anodes and LiFePO4 cathodes.
• Assembled batteries showed no fire or smoke upon nail penetration, indicating enhanced safety.

Conclusions:

• The GDIL-based iMembrane is a promising ion-conductive material for advanced energy storage.
• The iMembrane enhances the safety and energy density of lithium batteries due to its stability and compatibility.
• The developed material offers a viable pathway for creating safer, high-performance nonprotonic ionic membranes.