Synthesis and Li⁺ conduction study of solid ionic liquids derived from Zwitterion modified metal-organic framework...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Fast ion-conduction channels are crucial for advancing lithium-ion solid-state electrolytes (LiSSEs).
• Improving ion transfer and Li+ migration number are key objectives for high-performance LiSSEs.

Purpose of the Study:

• To report a new type of LiSSE based on metal-organic frameworks (MOFs) covalently modified with Li+ ionic liquids.
• To investigate the structure-property relationships and performance of the novel UiO-66-APS⋅xLiTFSI material.

Main Methods:

• Synthesis of UiO-66-MOF covalently modified with amino-1-propane sulfonate (APS) and lithium bis(trifluoromethane) sulfonimide (LiTFSI).
• Characterization of the material's structure, component effects, and ionic conductivity.
• Measurement of ionic conductivity and Li+ transference number (tLi+) over a range of temperatures.

Main Results:

• The UiO-66-APS⋅2.7LiTFSI material exhibits Li+ conduction over two orders of magnitude higher than its counterpart ionic liquid.
• Achieved ionic conductivity of 3.5 × 10⁻⁴ S cm⁻¹ and a Li+ transference number of 0.83 at room temperature.
• Conductivity increases with temperature, reaching 1.33 × 10⁻² S cm⁻¹ at 100 °C, following Arrhenius-type dependence.

Conclusions:

• The novel MOF-based LiSSE provides ordered channels and abundant hopping sites for efficient Li+ transmission.
• The material demonstrates high ionic conductivity, high Li+ transference number, and excellent safety features (non-flammability, non-leakage).
• This work presents a promising strategy for developing high-performance and safe LiSSEs for next-generation energy storage.