Three-Dimensional Polypyrrole-Decorated CuCo 2 S 4 Nanowires Anchored on Nickel Foam: A Promising Electrode for High-Performance Supercapacitors.

The exploitation of high-performance supercapacitors is crucial to promote energy storage technologies. Benefiting from the three-dimensional conductive micronanostructures and high specific capacity of the PPy@CuCo 2 S 4 @NF (polypyrrole/copper cobalt sulfide/nickel foam) composite electrode, this electrode exhibits a high specific capacity of 1403.21 C g -1 at 1 A g -1 and a capacitance retention of 85.79% after 10,000 cycles at 10 A g -1 . The assembled PPy@CuCo 2 S 4 @NF//AC aqueous hybrid supercapacitor (AHSC) reveals a wide operating potential window of 1.5 V and achieves a high specific capacity of 322.52 C g -1 at 1 A g -1 and a capacitance retention of 86.84% after 15,000 cycles at 10 A g -1 . The AHSC also exhibits a high power density of 733.69 W kg -1 at an energy density of 67.19 W h kg -1 , surpassing those of previously reported spinel-based supercapacitors. Ex situ X-ray diffraction and X-ray photoelectron spectroscopy results show that the CuCo 2 S 4 spinel structure changes to CuS 2 and CoS 2 cube structures, and the oxidation states of Cu and Co increase during charging and discharging processes. Density functional theory calculations suggest a superior conductivity for CuCo 2 S 4 compared to that for CuCo 2 O 4 , demonstrating that CuCo 2 S 4 has superior electrochemical performance. These findings attest to the considerable potential of the spinel materials for advanced energy storage applications.