PVP-assisted growth of Ni-Co oxide on N-doped reduced graphene oxide with enhanced pseudocapacitive behavior

Abstract

Herein, NiCo2O4/N-rGO nanocomposites were prepared by using solvothermal method and hydrothermal method. The specific surface area of the composite material reaches 99.38 m2 g−1, and NiCo2O4/N-rGO shows a high specific capacitance of 2090 F g−1 at a current density of 1 A g−1. When the current density reaches 10 A g−1, the electrode material still maintains the specific capacitance of 1257.5 F g−1 and the capacitance retention rate is 96.19% after 5000 cycles, which demonstrates that NiCo2O4/N-rGO nanocomposites have high activity, large specific capacitance and good rate performance as electrode materials for supercapacitors. Furthermore, solid-state asymmetric supercapacitor (ASC) is assembled in sealing form with NiCo2O4/N-rGO as positive electrode, active carbon (AC) as negative electrode and polyving akohol (PVA)-KOH as gel electrolyte. The relevant electrochemical test data show that the specific capacitance retention of the supercapacitor device is still 95.67% after 10,000 cycles, and the maximum energy density is 20.10 Wh kg−1 at a power density of 720.71 W kg−1, indicating that the device has excellent rate capability and cycle stability.