Design of Gel Electrolyte Bearing Redox Additive for High‐Performance Functional Supercapacitors

Abstract In advanced supercapacitor applications, redox‐based electrolyte systems, particularly the synergistic potential of benzoquinone, glycerol, and phosphoric acid, plays a crucial role. However, the poor electrochemical stability of these systems limits their practical use. Benzoquinone, known for its high redox activity, was incorporated into glycerol as a stable host‐gel matrix and combined with phosphoric acid to produce a high‐ion‐conductivity electrolyte. In this study high electrochemical stability and improved charge–discharge kinetics of redox‐mediated supercapacitors were systematically addressed. The findings highlight the potential of this unique electrolyte system to contribute to the development of high‐performance and environmentally friendly energy storage devices for diverse applications. In this regard, a comparative study was conducted on aqueous and nonaqueous glycerol (Gly)/phosphoric acid (P) systems, where benzoquinone (BQ) was introduced as a redox mediator in varying fractions. This research provides valuable insights into the design and optimization of electrolyte compositions for next‐generation supercapacitors with enhanced efficiency and sustainability. Furthermore, the devices assembled with Gly3P50BQ exhibited a high specific energy of 48 Wh kg⁻¹ at 150 W kg⁻¹ and demonstrated a superior capacitance retention rate of 95% after 10,000 charge–discharge cycles.