Improving the Electrochemical Performance of Zinc Sulfides by Iron Doping Toward Supercapacitor Applications

The rational design of heterostructured Fe-doped ZnS microspheres (FeZnS-MS) and their use as electrode materials for supercapacitors (SCs) is proposed. FeZnS-MS are mounted on a Ni foam substrate to develop high-activity positive electrodes for SCs. The morphological and electrochemical performances of the hydrothermally synthesized FeZnS-MS are investigated, revealing the formation of microspherical Fe-doped ZnS nanocubes. Different Fe ratios (0.1, 0.2, and 0.3) are successfully introduced to ZnS without impurities, whereas two phases are produced when the percentage is increased to 0.4. Notably, under a current density of 2 A g-1, the Zn0.7Fe0.3S nanocomposite showed an exceptional specific capacitance of 575 F g-1, compared to the moderate value (200 F g-1) achieved by ZnS. At 0.5 and 1 A g-1, the Zn0.7Fe0.3S electrode presented an even better specific capacitance of 700 and 604.5 F g-1, respectively. Using this electrode, a hybrid supercapacitor system is developed and delivered 11 Wh kg-1 and a high specific power of 591.2 W kg-1. The evaluation of FeZnS-MS electrochemical properties as an SC electrode is investigated in this work. Increased capacitance from 200 F g-1 for ZnS to 575 F g-1 for Zn0.7Fe0.3S at the current density of 2 A g-1.image