Ionicity Analysis of Silylamine-Type Reversible Ionic Liquids as a Model Switchable Electrolyte

Separation of the electrochemical product from an electrolyte can add challenges to the overall process. Use of a switchable electrolyte offers the possibility to reduce or eliminate these separation challenges while maintaining high conductivity. Reversible ionic liquids (RevILs) are a type of switchable solvent that could be used as a switchable electrolyte. Switchable solvents are solvents that can have dramatic step-changes in their properties with the introduction of an external stimulus, in this case CO2. In order to determine the feasibility of using TEtoxySA-RevIL, which behaves similarly to protic ionic liquids, as an electrolyte an ionicity analysis utilizing binary mixtures of the RevIL and organic solvents were studied to determine the ionic behavior of the system. Both protic and aprotic solvents with a broad range of dielectric constants were used in order to elucidate the ionicity of the RevIL mixtures. When in the pure RevIL state, the conductivity is prohibitively low due to a heightened viscosity and poor ion mobility due to hydrogen bonding and coulometric attraction. We found that in the presence of protic solvents with high dielectric constants the conductivity of the RevIL increased by up to four orders of magnitude and achieved ideal ionicity.