Structure-Property Relationships of Silylamine-Type Reversible Ionic Liquids for Use as a Switchable Electrolyte

Abstract

Switchable electrolytes, whose properties (i.e., conductivity and polarity) can be switched dramatically are very useful. They can address problems associated with multiple electrochemical systems: (1) the need to separate products from the electrolyte after electro-organic syntheses, and; (2) the desire to stop the acceleration of electrochemical reactions in energy storage devices during thermal excursions. Silylamine-type reversible ionic liquids (RevILs) in co-solvents were used as switchable electrolytes in this work. The silylamine RevILs in co-solvents can have a dramatic change in conductivity when switching from a RevIL state to a molecular liquid (state) when heat is applied. The silylamines also have significant changes in polarity with switching. The fundamental silylamine structure-property relationships that can be tuned to control relevant properties such as conductivity, viscosity, thermal switch temperature, and solubility were investigated. In addition, these silylamine RevILs were tested with the addition of metal salts, which were found to increase the conductivity in both the RevIL and ML states. By tailoring the silylamine RevIL structures, the thermo-physical properties for the electrochemical application can be met.