Inorganic-Organic Double Network Ionogels Based on Silica Nanoparticles for High-Temperature Flexible Supercapacitors

Herein, we demonstrate an inorganic-organic doublenetworkgel electrolyte consisting of a silica particle network and a poly-2-hydroxyethylmethacrylate network in which 1-butyl-3-methylimidazolium tetrafluoroborateionic liquids are confined. The as-synthesized double network ionogelelectrolytes exhibited high ion conductivity of 3.8 to 12.8 mS cm(-1) over a wide temperature range of 30 to 150 & DEG;Cand mechanical integrity with a maximum toughness of 1.8 MJ m(-3) at 30 & DEG;C. These remarkable properties of theionogel were associated with the formation of an optimal physicalnetwork of the silica nanoparticles in the colloidal dispersion. Accordingly,a flexible supercapacitor using ionogel electrolytes and reduced grapheneoxide electrodes delivered energy and power densities of 48 Wh kg(-1) and 4 kW kg(-1), respectively, evenat a high temperature of 120 & DEG;C, demonstrating excellent long-termstability that retains 93% of the initial capacitance even over 10,000charge/discharge cycles at 120 & DEG;C.

Automated summary

In this study, an inorganic-organic double network gel electrolyte with high ion conductivity and mechanical integrity was demonstrated. The gel consisted of a silica particle network and a poly-2-hydroxyethylmethacrylate network, with confined 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquids. The gel showed excellent properties attributed to the optimal physical network formed by the silica nanoparticles.