Tetrakis(pentafluoroethyl)gallate, [Ga(C₂ F₅ )₄ ]^- , Ionic Liquids

Area of Science:

• Materials Science
• Electrochemistry
• Organic Chemistry

Background:

• Ionic liquids (ILs) are salts that are liquid at ambient temperatures, offering unique properties for various applications.
• Imidazolium-based ILs are widely studied due to their tunable properties and stability.
• Developing novel ILs with enhanced performance, particularly for electrochemical applications, remains an active area of research.

Purpose of the Study:

• To synthesize and characterize new imidazolium-based tunable aryl alkyl ionic liquids (TAAILs) featuring the tetrakis(pentafluoroethyl)gallate anion, [Ga(C2F5)4]-.
• To investigate the physicochemical properties (viscosity, conductivity, electrochemical window) of these novel TAAILs.
• To compare the performance of TAAILs with standard imidazolium cations like EMIM and BMIM.

Main Methods:

• Synthesis of novel imidazolium-based TAAILs with varying phenyl substituents and alkyl chain lengths.
• Characterization of TAAILs including viscosity, conductivity, and electrochemical window measurements.
• Electrochemical stability testing to determine decomposition voltages and long-term stability.

Main Results:

• Achieved remarkably low viscosity of 29 cP at 25°C for [BMIM][Ga(C2F5)4].
• Observed electrochemical instability in EMIM and BMIM gallates, decomposing at 1.5 V.
• 2-Me-substituted gallate-TAAILs showed slow decomposition, while other gallate-TAAILs exhibited no decomposition.
• Identified gallate-TAAILs with electrochemical windows up to 5.15 V and viscosities between 66-162 cP.

Conclusions:

• Gallate-TAAILs offer tunable properties with potential for low viscosity and high electrochemical stability.
• While some standard cations showed instability, specific gallate-TAAILs demonstrate excellent electrochemical performance.
• These novel gallate-TAAILs are promising candidates for advanced electrolyte applications in electrochemical devices.