Iron‐Cobalt Bi‐Metallic Sulfide Nanowires on Ni Foam for Applications in High‐Performance Supercapacitors

Abstract Supercapacitors do not only exhibit the traditional high power density of capacitors, but also show the high energy density characteristic for batteries. In addition, fast charging, outstanding rate of magnification, and safety as well as pollutant‐free characteristics make supercapacitors unprecedented for applications and development prospects in the field of energy storage. In this study, a facile two‐step hydrothermal method was presented for the synthesis of FeCo 2 S 4 nanowire structures directly formed on nickel (Ni) foam. The as‐prepared FeCo 2 S 4 samples were characterized using X‐ray powder diffraction and scanning electron microscopy. The electrochemical performance of the as‐prepared FeCo 2 S 4 electrodes is studied by cyclic voltammetry (CV), galvanostatic charge‐discharge measurements (CD), and cycle stability tests. The as‐prepared FeCo 2 S 4 nanowires exhibit a high specific capacitance of about 337 mAh g −1 at a current density of 2 A g −1 in 3 M KOH solution. After 2000 cycles at 6 A g −1 , 90 % of the initial capacity is retained, showing the excellent stability of the prepared material. At a high current density of 12 A g −1 , the capacity can reach 273 mAh g −1 with 81 % remaining, exhibiting outstanding rate characteristics. The superior electrochemical performance can be attributed to the high specific surface area, ion/electron transportability, and the excellent electrical conductivity of the active material itself. Therefore, as the most advanced energy storage material, FeCo 2 S 4 will have great development prospects in terms of energy conversion, storage, and electrocatalysis.