A Binder-Free Hybrid of CuO-Microspheres and rGO Nanosheets as an Alternative Material for Next Generation Energy Storage Application

Herein, a facile and effective ultrasonication assisted approach has been employed to integrate hydrothermally produced CuO microspheres (CMS) with chemically synthesized reduced graphene oxide conducting nanosheets (CRGO), yielding a new composite material (CSCO). The synthesized materials have been probed by various characterization techniques. The electrochemical performance of all the materials are thoroughly studied by cyclic voltammetry (CV), galvanostatic charging-discharging (GCD) and electrochemical impedance spectroscopy (EIS) techniques. At a current density of 0.125 A g−1, CSCO demonstrates an excellent specific capacitance of 244 F g−1 (more than six times higher than CMS and CRGO) and the maximum energy and power density values of 8.47 Wh kg−1 and 73.49 W kg−1, respectively. Additionally, it exhibits high rate performance (retains 82.78 % of its initial capacitance even at a high current density of 0.5 A g−1) and long cycle life (∼ 90 % up to 1000 cycles), confirming the robustness and high stability of the composite on the electrode surface. The superior electrochemical performance can be attributed to the positive synergistic effects between CMS and CRGO, providing mechanical robustness and short diffusion path for charge transfer, leading to high conductivity. Distinguishing features such as being binder-free, ease of preparation, high energy and power density, make CSCO a potential candidate for high performance supercapacitors.