Comparative studies on electrochemical cycling behavior of two different silica-based ionogels.

We report a comparative study of two silica-based ionogel electrolytes for electrochemical cycling applications. The ionogels considered represent two classes of gel networks, a covalently formed network generated by the polymerization of tetramethoxysilane catalyzed by formic acid, and a network formed by weak intermolecular forces obtained by mixing fumed silica nanopowder with ionic liquid. In both cases, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide is utilized as the ion conductor in the gel network. With increasing temperature it is shown that the electrochemical stability window is reduced, the conductivity of the electrolyte is increased, and the double layer capacitance is increased for both types of ionogels. Long-term stability of the two ionogels is excellent, with 90% capacitance retained after 10,000 repetitive CV cycles at 100 °C. Our results indicate that both of these ionogel electrolytes are promising for application in solid-state electrochemical systems at high temperature. [ABSTRACT FROM AUTHOR]