Synthesis, characterization and supercapacitor application of ionic liquid incorporated nanocomposites based on SPSU/Silicon dioxide

In this study, we report about novel polymer electrolytes containing sulfonated polysulfone (SPSU) as the polymer matrix, silicon dioxide (SiO₂) as nano additive and ionic liquid (1-Ethyl-3-methyl-imidazolium tetrafluoroborate) IL) as a softening agent. In addition, the physical and chemical properties of ionic liquid containing nanocomposite gel polymer electrolytes were studied and subsequently the optimized electrolyte was used to assemble the supercapacitor device. Nanocomposite gel polymer electrolytes demonstrated higher thermal stability and lower glass transition temperatures (T_g) required for supercapacitor application. The ion conductivity of the nanocomposite polymer electrolytes was investigated using a dielectric-impedance analyzer at various temperatures. The highest conductivities were obtained for the samples SPSU/0.1IL and SPSU/%3n SiO₂/0.2IL with values 3.1 × 10⁻⁴ and 3.2 × 10⁻³ S cm⁻¹ at 100 °C, respectively. In addition, symmetrical cell formation based on Al/C/SPSU/%3nSiO₂/0.2IL/C/Al showed a maximum specific capacitance of 134.1 F g⁻¹ at 1 A g⁻¹. The same cell also yielded a maximum energy density in supercapacitor as 18.6 Wh kg⁻¹ at a power density of 1089 W kg⁻¹.