Enhanced electrochemical performance of CuCo₂S₄/carbon nanotubes composite as electrode material for supercapacitors

CuCo₂S₄ is regarded as a promising electrode material for supercapacitor, but has inferior conductivity and poor cyclic stability which restrict its wide-range applications. In this work, hierarchically hybrid composite of CuCo₂S₄/carbon nanotubes (CNTs) was synthesized using a facile hydrothermal and sulfuration process. The embedded CNTs in the CuCo₂S₄ matrix provided numerous effective paths for electron transfer and ion diffusion, and thus promoted the faradaic reactions of the CuCo₂S₄ electrode in the energy storage processes. The CuCo₂S₄/CNTs-3.2% electrode exhibited a significantly increased specific capacitance of 557.5 F g^-1 compared with those of the pristine CuCo₂S₄ electrode (373.4 F g^-1) and CuO/Co₃O₄/CNTs-3.2% electrode (356.5 F g^-1) at a current density of 1 A g^-1. An asymmetric supercapacitor (ASC) was assembled using the CuCo₂S₄/CNTs-3.2% as the positive electrode and the active carbon as the negative electrode, which exhibited an energy density of 23.2 Wh kg^-1 at a power density of 402.7 W kg^-1. Moreover, the residual specific capacitance of this ASC device retained 85.7% of its original value after tested for 10,000 cycles, indicating its excellent cycle stability.