A liquid electrolyte based on binary solvent systems of ethylene carbonate (EC), dimethyl carbonate (DMC) and lithium bis(trifluoromethane)sulfonimide (LiTFSI) salt incorporating with acrylic acid (AA) monomer was synthesized. The ionic conductivity studies revealed that the conductivity of the liquid electrolyte was enhanced from 2.16 × 10−3 to 2.24 × 10−3 S cm−1 at room temperature after the addition of 0.1 mol/kg AA due to the presence of a carbonyl group in AA structure. The viscosity and the temperature dependence of the ionic conductivity followed an Arrhenius equation. Interactions of the EC/DMC, LiTFSI and AA were characterized by Fourier transform infrared spectroscopy analysis. The electrochemical performance of the liquid electrolyte towards electric double layer capacitor (EDLC) was investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. EDLC performances demonstrated that the supercapacitors exhibited specific capacitance ∼24.01 F/g at 5 mV/s. The life cycle test revealed that supercapacitor cell incorporated with synthesized liquid electrolyte possessed excellent stability and coulombic efficiency even after 4000 cycles. •Electrolyte based on Ethylene carbonate, dimethyl carbonate and LiTFSI was prepared.•Acrylic acid was added in above electrolyte and its affect was analysed.•Ionic conductivity studies revealed that sample AA 0.1 has highest conductivity.•The synthesized electrolyte showed enhance performance for supercapacitor.•The synthesized electrolyte based supercapacitor was highly stable.