The electrochemical and charge storage performance of a fluorine-free structurally flexible pyrrolidinium-based ionic liquid hybrid electrolyte (HILE) in a symmetric graphite-based supercapacitor is thoroughly investigated. The HILE revealed thermal decomposition at 270 ºC, a glass transition (T _g) temperature of −73 ºC, and ionic conductivity of 0.16 mS cm ⁻¹ at 30 ºC. A systematic variable temperature ¹H and ³¹P NMR spectroscopy and diffusometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) are employed. HILE-based supercapacitor demonstrated a notable specific capacitance of 186 Fg ⁻¹ at a scan rate of 1 mVs ⁻¹ and a specific capacitance of 122 Fg ⁻¹ at a current density of 0.5 Ag ⁻¹. The maximum energy density of 49 Wh kg ⁻¹, a power density of 370 W kg ⁻¹ at a current density of 0.5 A g ⁻¹ and a potential window of 4V were obtained. HILE displayed a promising electrochemical performance over a wide potential window of 4V and temperature range (−20 ºC to 90 ºC) in a symmetric graphite supercapacitor.