Facile synthesis and superior electrochemical performances of CoNi2S4/graphene nanocomposite suitable for supercapacitor electrodes

A facile physical approach was developed to construct the CoNi2S4/graphene nanocomposite. The as-obtained samples are characterized and their corresponding electrochemical performances evaluated. Results show that the supercapacitor electrodes based on the CoNi2S4/graphene nanocomposite exhibit excellent pseudocapacitance behaviour enhanced by a synergistic effect. When the loaded amount of graphene is 5% (wt%), the maximum specific capacitance reaches up to 2009.1 F g(-1) at a discharge current density of 1 A g(-1) and the specific capacitance can be maintained at 755.4 F g(-1) at 4 A g(-1) after 2000 charge-discharge cycles. Furthermore, this electrode shows excellent rate capability (1046.4 F g(-1) at 20 A g(-1)) and better electrochemical reversibility. This enhancement in pseudocapacitance behaviour is due to the CoNi2S4/graphene interconnected conductive network which promotes not only electrolyte diffusion and efficient charge transport, but also prevents aggregation and volume expansion/contraction of electroactive materials. Hence one can see that the CoNi2S4/graphene nanocomposite is a promising electrode material for high-performance supercapacitors.