Electrochemical performance of rGO/MWCNT/CoS ternary composite for supercapacitor applications

Renewable energy systems and energy storage technologies gain significant attention in the present scenario due to the increasing global energy demand. The intriguing properties of supercapacitors make them a promising up-and-comer in electrochemical energy storage applications. The fabrication of hybrid capacitors, integrating the electric double layer and the pseudocapacitive materials, improves the performance of the supercapacitors. Herein, we report the synthesis of a ternary nanocomposite of reduced graphene oxide, multi-walled carbon nanotubes, and cobalt sulfide (rGO/MWCNT/CoS), employing a one-pot hydrothermal process. Both rGO and MWCNTs constitute an excellent matrix for hybrid supercapacitors owing to their exceptional conductivity and extraordinary carrier mobility. Their composites with metal sulfides demonstrate superior electrochemical properties due to the synergistic contributions. The pseudocapacitive CoS boosts up the specific capacitance of the system and functions as a spacing material to mitigate the graphene layer aggregation. The incorporation of MWCNTs improves the conductivity and cyclability of the composites by linking the graphene layers into a network structure. The electrochemical investigation of the rGO/MWCNT/CoS reveals that the ternary composite is a good choice as a supercapacitor electrode with a remarkable specific capacitance of 612 Fg−1 at 1 A/g and an appreciable cyclability of 93 % across 2000 cycles.