Sol-gel synthesis pathway and electrochemical performance of ionogels: A deeper look into the importance of alkoxysilane precursor

There is a great interest in the application of ionogels as electrolyte for energy storage devices due to their enhanced safety compared to conventional electrolytes. This work aims to shed light on an often-overlooked aspect of ionogel synthesis which is the impact of the precursors on the sol-gel reaction kinetics and the electrochemical properties of the resultant ionogels. Using time-resolved Raman spectroscopy the non-hydrolytic sol-gel synthesis of ionogels from four different alkoxysilane precursors were monitored. Their electrochemical performance as electrolyte for electric double-layer capacitors were characterised using cyclic voltammetry and electrochemical impedance spectroscopy. Our findings suggest that presence of ionic liquid does not impact the sol-gel process kinetics of all four formulations in the same manner. In addition, ionogel formulations with the longest gelation time demonstrated poor electrochemical properties caused by the further ingress of silica into the activated carbon electrodes. This was confirmed with EDX analysis.