High-temperature symmetric supercapacitor applications of anhydrous gel electrolytes including doped triazole terminated flexible spacers

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

Herein, we demonstrate an inorganic-organic double network gel electrolyte consisting of a silica particle network and a poly-2-hydroxyethyl methacrylate network in which 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquids are confined. The as-synthesized double network ionogel electrolytes exhibited high ion conductivity of 3.8 to 12.8 mS cm-1 over a wide temperature range of 30 to 150 °C and mechanical integrity with a maximum toughness of 1.8 MJ m-3 at 30 °C. These remarkable properties of the ionogel were associated with the formation of an optimal physical network of the silica nanoparticles in the colloidal dispersion. Accordingly, a flexible supercapacitor using ionogel electrolytes and reduced graphene oxide electrodes delivered energy and power densities of 48 Wh kg-1 and 4 kW kg-1, respectively, even at a high temperature of 120 °C, demonstrating excellent long-term stability that retains 93% of the initial capacitance even over 10,000 charge/discharge cycles at 120 °C.

Highly Flexible and Tailorable Cobalt-Doped Cross-Linked Polyacrylamide-Based Electrolytes for Use in High-Performance Supercapacitors

A novel hydrogel polymer electrolyte was prepared by incorporation of 1,4-butanediol diglycidyl ether (BG) to cross-linked polyacrylamide (PAM). The electrolyte (PAMBG) was modified with cobalt (II) sulfate with various doping ratios (PAMBGCoX) to increase the capacitance by increasing faradaic reactions. The supercapacitor device assembly was performed by using active carbon (AC) electrodes and hydrogel polymer electrolytes. The specific capacitance of the PAMBGCo5 device indicated 130 F g^-1 , which is at least a seven-fold improvement due to the insertion of Co as a redox component. The electrolyte device, PAMBGCo5, displays superior performance having an energy density of 38 Wh kg^-1 at a power density of 500 W kg^-1 . Additionally, with the same hydrogel, the device performed 10,000 galvanostatic charge-discharge cycles via retaining 91% of the initial capacitance. A cost-effective electrolyte, PAMBGCo5, was tested in a carbon-based supercapacitor under bent and twisted conditions at various angles, confirming the robustness of the device.