A novel redox-mediated gel polymer electrolyte for high-performance supercapacitor

► A novel redox-mediated gel electrolyte was prepared by doping p-benzenediol. ► The new gel electrolyte has a high ionic conductivity of 34.8 mS cm −1. ► The supercapacitor with the electrolyte shows a high C s of 474.29 F g −1. ► The energy density of the supercapacitor with the electrolyte reaches 11.31 W h kg −1. A supercapacitor based on a novel redox-mediated gel polymer electrolyte (PVA–H 2SO 4–P–benzenediol) and activated carbon electrodes is assembled. The electrochemical properties of the supercapacitor are evaluated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. It is found that the supercapacitor exhibits large specific capacitance (474.29 F g −1), high energy density (11.31 W h kg −1), and excellent cyclical stability. The good performance for the supercapacitor is due to the capacity-storage mechanism combination of the electrical double layer capacitance and Faradaic pseudocapacitance by p-benzenediol/p-benzoquinone in the electrolyte.