High power density supercapacitor devices based on nickel foam–coated rGO/MnCo2O4 nanocomposites

New nanocomposite electrode material of rGO/MnCo 2 O 4 was freely loaded on flexible substrate on nickel foam and prepared by a simple, cost-effective, and eco-friendly pathway. The results show that the spinel manganese cobaltite (MnCo 2 O 4 ) with reduced graphene oxide (rGO) nanocomposite forms a uniform deposit and densely covers on the nickel foam (NF). The electrochemical measurements were investigated in three methods, such as cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). The synergistic effects from rGO and MnCo 2 O 4 deliver outstanding an excellent electrochemical performance that was not realized by any of these components alone. The electroactive material exhibits a high specific capacitance of C sp = 808 F/g at 2 mV/s in 1 M KOH solution. Furthermore, this device delivers an excellent power density of P = 7658 W/kg and a high energy density of E = 15.2 Wh/kg. More importantly, cycling retention is 135% after 1000 charge/discharge cycles. This study proposes that the as-prepared (rGO/MnCo 2 O 4 )/nickel foam has a potential application and a promising candidate for energy storage devices.