Redox-active electrolyte-based MnWO₄//AC asymmetric supercapacitors

Finding supercapacitive materials with high energy and power densities has attracted significant interest in recent years. Herein, we are reporting layered MnWO₄ nanostructure for supercapacitor applications. MnWO₄//AC asymmetric cell was fabricated by using hydrothermally synthesized MnWO₄ nanostructure as a cathode and activated carbon as an anode. Prior to device fabrication, the structural and electrochemical properties of MnWO₄ were thoroughly studied. MnWO₄//AC asymmetric cell with KOH electrolyte showed specific capacitance and energy density of 90 F/g (at 1 mA/cm²) and 51 Wh/kg, respectively. Upon addition of redox-active KI into KOH, both the specific capacitance and energy density were significantly enhanced (144 F/g and 90 Wh/Kg, respectively). The enhanced electrochemical properties of MnWO₄//AC asymmetric cell can be attributed to the high-speed solution-phase faradic reactions contributed by KI redox species in the KOH electrolyte.