Employing Redox‐Active Additives for Enhanced Charge Polarization and Twofold Higher Energy Density in Supercapacitor

Remarkable improvement in the polarization and charge transport at solid–solid electrode–electrolyte interface due to incorporation of a redox-active additive sodium molybdate (Na2MoO4) is demonstrated. The presence electrochemically active oxide center along with Na+ facilitates hopping-based ionic liquid leading higher conductivity twofold increase specific capacitance (0.009 0.018 F cm−2). This drives 200% energy density (0.76–1.7 µW h cm−2) 2.5 times rate capability (10 000 mV s−1) solid-state supercapacitor. Importantly, power density, non-Faradic nature, cyclability remain unaltered, resulting performance exceeding several electrolyte-based supercapacitors. Thus, results established here through use establish robustness approach practicality device besides providing transformative opportunities tuning devices.