Engineering accordion-like Fe-doped NiS2 enabling high-performance aqueous supercapacitors and Zn-Ni batteries

Abstract

Metal-organic frameworks are of great potential as electrode material in aqueous energy storage applications. In this work, a Fe-doped accordion-like Fe/NiS2 is fabricated by a simple hydrothermal treatment followed by anion exchange strategy. The Fe/NiS2 possesses large specific surface area and enhanced electrical conductivity ascribed to the unique 2D structure and rich defects aroused by Fe doping. By controlling the molar ratio of Ni:Fe to 1:0.01, the obtained Fe0.01NiS2 shows high specific capacitance (1965.9F/g at 0.5 A/g), the assembled Fe0.01NiS2//AC exhibits satisfying specific capacitance (183.11F/g at 0.2 A/g) and cycling property (75.6 % capacitance retention after 15,000 cycles). The aqueous Fe0.01NiS2//Zn also displays high capacity (193.33 mAh g−1 at 0.25 A/g) and cycling stability. The density functional theoretical calculations demonstrate that the Fe-doping can boost the charge storage ability and optimize adsorption energy of OH–. This work reveals a new method for construction of metal ion-doped MOF-based electrode materials for aqueous and other energy storage application.