Effect of redox additive in aqueous electrolyte on the high specific capacitance of cation incorporated MnCo2O4@Ni(OH)2 electrode materials for flexible symmetric supercapacitor

The electrochemical energy storage of the transition metal oxide/hydroxide is mainly governed by the reversible redox reaction. The present study emphasizes the possibility of enhancing the electrochemical performance through cation intercalated-MnCo2O4@Ni(OH)2 hybrid nanoflowers in KOH/K3[Fe(CN)6] mixed electrolyte. Cation intercalation played a crucial role in enhancing the electrochemical properties. Outstanding specific capacitance values of ~750 F g−1 and 5413.12 F g−1 at 5 A g−1 current density were recorded in 6 M KOH and KOH/K3[Fe(CN)6] mixed electrolytes, respectively. The electrochemical reaction involved in the energy storage of cation intercalated-MnCo2O4@Ni(OH)2 electrode in KOH/K3[Fe(CN)6] mixed electrolyte was investigated in detail. The unsymmetrical behaviour in the charging/discharging profile of the electrode material was attributed to the use of mixed electrolyte, KOH/K3[Fe(CN)6] in electrochemical analysis. A flexible all-solid-state symmetric supercapacitor device was fabricated and the device delivered ~1656.6 F g−1 discharge capacitance with 82.83 Wh kg−1 energy and 300 W kg −1 power density at 1 A g−1 current density.