Facile fabrication of CuCo2S4 nanoparticles/MXene composite as anode for high-performance asymmetric supercapacitor

Abstract

A novel organ-like Ti₃C₂T_x/CuCo₂S₄ composite was synthesized via a hydrothermal method by forming well-defined and uniformly dispersed CuCo₂S₄ nanoparticles on Ti₃C₂T_x nanosheets. Mainly owing to the increase in conductivity, electron/ion transport capacity and the structural stability of the Ti₃C₂T_x/CuCo₂S₄ composite in 6 M KOH electrolyte, the MXene/CuCo₂S₄ composite material exhibited enhanced performance (992.3 C g⁻¹ at 1 A g⁻¹) compared with pristine CuCo₂S₄ (675.2 C g⁻¹ at 1 A g⁻¹) and Ti₃C₂T_x MXene (92.3 C g⁻¹ at 1 A g⁻¹). In addition, an asymmetric supercapacitor (ASC) was built with Ti₃C₂T_x MXene/CuCo₂S₄ as the positive electrode and activated carbon (AC) as the negative electrode (MXene/CuCo₂S₄//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/CuCo₂S₄ as a promising electrode for supercapacitors.