Fluorinated Linkers Enable High-Voltage Pyrrolidinium-based Dicationic Ionic Liquid Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Ionic liquids (ILs) are crucial electrolytes in energy storage.
• Developing high-voltage electrolytes with enhanced stability is essential for next-generation batteries.

Purpose of the Study:

• To synthesize and characterize novel fluorinated, pyrrolidinium-based dicationic ionic liquids (FDILs).
• To evaluate the impact of fluorination on electrochemical, thermal, and ion transport properties.
• To assess FDILs as electrolytes for high-voltage lithium-ion batteries.

Main Methods:

• Synthesis of FDILs with fluorinated ether linkers and TFSI/FSI counterions.
• Comparative analysis of FDILs with non-fluorinated counterparts.
• Electrochemical stability, thermal stability, and ion transport measurements.
• Systematic evaluation of Li-salt impact on dicationic IL characteristics.

Main Results:

• FDILs exhibit unprecedented electrochemical stability (up to 7 V) and thermal stability (up to 370°C).
• Ion transport capabilities reach up to 1.45 mS cm⁻¹.
• Fluorinated linkers significantly enhance properties compared to non-fluorinated analogs.
• FDILs demonstrate superior performance as electrolytes for high-voltage lithium-ion batteries.

Conclusions:

• Fluorinated dicationic ionic liquids are promising high-performance electrolytes.
• FDILs offer a viable alternative for next-generation high-voltage energy storage systems.
• The fluorinated ether linker is key to achieving enhanced stability and performance.