Low-cost synthesis and electrochemical characteristics of ternary Cu-Co sulfides for high performance full-cell asymmetric supercapacitors

Abstract Ternary Cu-Co sulfides, CuCo 2 S 4 , with an average size of about 20–60 nm were synthesized via a novel and low-cost method. Characterization results show that the as-obtained CuCo 2 S 4 nanoparticles belong to cubic phase with high crystallinity. Meanwhile, CuCo 2 S 4 nanoparticles exhibit excellent electrochemical performances, i.e. : the specific capacitances as high as 443.7 F/g at a current density of 1 A/g, and good cyclic stability (83.8% capacitance retention after 10000 charge-discharge cycles). More importantly, full-cell asymmetric supercapacitors based on CuCo 2 S 4 nanoparticles and activated carbon were successfully assembled, which achieving higher specific capacitance of 274.5 mF/cm 2 at the current density of 3 mA/cm 2 . After 5000 charge/discharge cycles, these full-cell asymmetric supercapacitors can still remain 94.7% of the initial specificcapacitance. Besides, they can be charged and discharged to drive some electric elements. All these outstanding results demonstrate the promising potential application of CuCo 2 S 4 nanoparticles in the field of energy storage.