Facile fabrication of CuCo 2 S 4 nanoparticles/MXene composite as anode for high-performance asymmetric supercapacitor

A novel organ-like Ti 3 C 2 T x /CuCo 2 S 4 composite was synthesized via a hydrothermal method by forming well-defined and uniformly dispersed CuCo 2 S 4 nanoparticles on Ti 3 C 2 T x nanosheets. Mainly owing to the increase in conductivity, electron/ion transport capacity and the structural stability of the Ti 3 C 2 T x /CuCo 2 S 4 composite in 6 M KOH electrolyte, the MXene/CuCo 2 S 4 composite material exhibited enhanced performance (992.3 C g −1 at 1 A g −1 ) compared with pristine CuCo 2 S 4 (675.2 C g −1 at 1 A g −1 ) and Ti 3 C 2 T x MXene (92.3 C g −1 at 1 A g −1 ). In addition, an asymmetric supercapacitor (ASC) was built with Ti 3 C 2 T x MXene/CuCo 2 S 4 as the positive electrode and activated carbon (AC) as the negative electrode (MXene/CuCo 2 S 4 //AC). This ASC device exhibited a specific capacity of 269.4 C g −1 at 1 A g −1 in the potential range from 0 to 1.6 V. The maximum specific energy of 66.8 W h kg −1 at a specific power of 895.1 W kg −1 was obtained with an 88.2% capacity retention after 10 000 charge–discharge cycles at a current density of 8 A g −1 . Moreover, the ASC device also showed 89.7% capacity retention at floating time over 200 h at 8 A g −1 . These results illustrate MXene/CuCo 2 S 4 as a promising electrode for supercapacitors.