An asymmetric supercapacitor with ultrahigh energy density based on nickle cobalt sulfide nanocluster anchoring multi-wall carbon nanotubes hybrid

Abstract The development of novel electrode materials with high energy density and long cycling life is critical to realize electrochemical capacitive energy storage for practical applications. In this paper, the hybrids of nickle cobalt sulfide/multi-wall carbon nanotubes (NiCo 2 S 4 /MWCNTs) with different contents of MWCNTs are prepared using a facile one-pot solvothermal reaction. As novel active materials for supercapacitors, the electrochemistry tests show that the hybrid of NiCo 2 S 4 /MWCNTs-5 is able to deliver a high specific capacitance of 2080 F g −1 at the current density of 1 A g −1 , even superior rate capability of 61% capacitance retention after a 20-fold increase in current densities, when the content of MWCNTs is up to 5%. More importantly, an asymmetric supercapacitor assembled by NiCo 2 S 4 /MWCNTs-5 as positive electrode and reduced graphene oxide (rGO) as negative electrode delivers a high energy density of 51.8 Wh Kg −1 at a power density of 865 W kg −1 , and 85.7% of its initial capacitance is retained at the current density of 4 A g −1 after 5000 charge-discharge cycles, exhibiting potential prospect for practical applications.