Preparation of polypyrrole-decorated MnO ₂ /reduced graphene oxide in the presence of multi-walled carbon nanotubes composite for high performance asymmetric supercapacitors

The present work demonstrates the preparation of polypyrrole-decorated MnO ₂ /rGO by oxidative polymerization method as well as in the presence of CNTs composites. The as-prepared nanocomposites are investigated by XRD, ATR-IR, Raman, TGA, and TEM techniques. Results illustrate polypyrrole with spherical nanoparticles covering the surface of MnO ₂ /rGO and CNTs in which CNTs are intercalated between MnO ₂ /rGO layers (Py@MnG2). In the meantime, the electrochemical performances for the obtained samples are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) experiments at 2 M KCl aqueous electrolyte. Owing to the presence of CNTs as well as the synergistic effect between polypyrrole and MnO ₂ /rGO layers, the electrochemical performance of Py@MnG2 shows high specific capacitance of 295.83 F g ⁻¹ in a three-electrode system. The asymmetric supercapacitor (ASC) is assembled with Py@MnG2 and microwave exfoliated graphite oxide (MrGO) as positive and negative electrode material respectively. The as-fabricated ASC device exhibits a high energy density of 11.22 Wh Kg ⁻¹ and power density of 807.67 W kg ⁻¹ at 1 A g ⁻¹ in the potential window of 0–1.6 V. Moreover, the ASC device shows good cycling stability (78.42%) after 1000 cycles at 200 mV s ⁻¹ .