Charge storage performance of a structurally flexible hybrid ionic liquid electrolyte

The electrochemical and charge storage performance of a fluorine-free structurally flexible hybrid pyrrolidinium-based ionic liquid electrolyte (HILE) in a symmetric graphite-based supercapacitor is thoroughly investigated. The HILE revealed thermal decomposition at above 230 degrees C, a glass transition (T-g) temperature of below -70 degrees C, and ionic conductivity of 0.16 mS cm(-1) at 30 degrees C. The chemical and electrochemical properties are investigated using a systematic variable temperature H-1 and P-31 NMR spectroscopy and diffusometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The supercapacitor demonstrated a notable specific capacitance of 186 F g(-1) at a scan rate of 1 mV s(-1) and a specific capacitance of 122 F g(-1) at a current density of 0.5 A g(-1). The maximum energy density of 48.8 Wh kg(-1), a power density of 450 W kg(-1) at a current density of 0.5 A g(-1), and a potential window of 4 V were obtained. Altogether, this study demonstrates that the new HILE can be used in symmetric graphite-based supercapacitors over a wide potential window of 4 V and a temperature range from -20 degrees C to 90 degrees C.