Facile and low-cost synthesis of cobalt-doped MnO2 decorated with graphene oxide for high performance 2.3 V aqueous asymmetric supercapacitors

Abstract

Efficient and novel cobalt doped MnO2 nanowires decorated with Graphene oxide was successfully synthesized with hydrothermal method and ultrasonic process. The nanocomposite phase was confirmed by XRD and XPS data. TEM and HRTEM analysis showed the good dispersion of MnO2 nanowires on graphene oxide sheets. Benefiting from the synergistic effect between cobalt-doped MnO2 nanowires and graphene oxide, the electrode material showed a satisfactory electrochemical performance with high specific capacitance of 397 F g−1 at 0.5 A g−1, high rate capability (328 F g−1 at 20 A g−1), and excellent capacitance retention only 2.5% decay after 4000 cycles at 10 A g−1 current density. As application for asymmetric supercapacitor device, the Cobalt doped MnO2 decorated with graphene oxide (MCo(0.25)/GO) electrode achieved a wide potential window up to 2.3 V with a high energy density of 35.3 Wh·kg−1 at power density of 590 W kg−1. Moreover, an energy density value of 25.8 Wh·kg−1 is maintained at high power density (5.6 kW kg−1). Therefore, the prepared MCo(0.25)/GO nanocomposite, with outstanding electrochemical performance, is considered as suitable and great potential application for supercapacitor device in the next generation.