Synergetic effect on enhanced electrochemical properties of MnO2 nanorods on g-C3N4/rGO nanosheet ternary composites for pouch-type flexible asymmetric supercapattery device

Abstract

In this work, one-dimensional MnO2 nanorods are distributed evenly over two-dimensional g-C3N4/rGO nanosheets using a simple hydrothermal approach. The structure, functional group, morphologies, elemental analyses and surface area of prepared samples have been investigated. Moreover, the electrochemical performance of MnO2/g-C3N4/rGO in 1 M Na2SO4 aqueous electrolyte solution was tested using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and capacitance retention. The MnO2/g-C3N4/rGO material has superior electrochemical performance than pure and binary electrode materials due to the high surface area of ternary composite (469.26 m2/g) compared to pure (38.083 m2/g). The ternary MnO2/g-C3N4/rGO electrode obtained the high specific capacitance of 716.6 Fg−1 at 1 Ag−1 and kept 97 % capacitance retention after 10,000 cycles at a current density of 10 Ag−1. Since the synergistic effects of MnO2 and g-C3N4/rGO improve electrochemical performance, the ternary composite is an excellent option for high-performance supercapacitors. Moreover, the pouch-type supercapattery device was assembled using MnO2/g-C3N4/rGO and activated carbon electrodes. The supercapattery device exhibits a maximum specific capacitance of 108.5 Fg−1 with 91.5 % capacitance retention after 10,000 cycles at a high current density of 10 Ag−1. The device achieved a high energy density of 48.6 Wh kg−1 at a power density of 899.9 W kg−1 in the operating potential value of 0–1.8 V. The fabricated supercapattery device was tested for real practical application by charging 30 s and attained a self-discharging time of 5 min.