CuCoS-MoS nanocomposite: a novel electrode for high-performance supercapacitors

Ternary transition metal sulfides have emerged as promising electrode materials for next-generation supercapacitors because of their potential ability to simultaneously ensure high conductivity and stability during electrochemical reactions. In the present investigation, MoS 2 incorporated CuCo 2 S 4 nanocomposites have been successfully synthesized using a hydrothermal technique. The structural, morphological, elemental and chemical properties of the prepared CuCo 2 S 4 -MoS 2 nanocomposite were investigated extensively. High resolution transmission electron microscopy imaging demonstrated the successful synthesis of CuCo 2 S 4 -MoS 2 nanocomposites. The electrochemical capacitor performance of the nanocomposite has been evaluated both in three-electrode and symmetric two-electrode systems. In the three-electrode cell, a specific capacitance of 820 F g −1 was achieved for the CuCo 2 S 4 -MoS 2 electrode at a current density of 0.5 A g −1 which is considerably higher than that of the CuCo 2 S 4 electrode (249 F g −1 ). We observed that the charge storage capacity, conductivity and stability of CuCo 2 S 4 improved significantly due to the incorporation of MoS 2 . Finally, an asymmetric supercapacitor was fabricated by assembling the CuCo 2 S 4 -MoS 2 electrode with an activated carbon electrode which demonstrated a large stable working potential window of 1.6 V. Excellent long-term cyclic stability of 89% retention after 1000 galvanostatic charge-discharge cycles was evident. As a solid state device, it delivered a high energy density of 38.22 W h kg −1 at a power density of 400 W kg −1 and lit up one red LED for 170 s, indicating its superiority over the conventional Cu-Co based supercapacitors. Hydrothermal incorporation of an MoS 2 nanosheet onto ternary metal sulfide enhances the specific capacitance resulting in an asymmetric supercapacitor (CuCo 2 S 4 -MoS 2 //AC) with ultra-high energy density and power density as well as wide potential window.