Investigation on the electrochemical properties of hydrothermally synthesized pure and Nickel doped Zinc Sulfide microspheres for supercapacitor electrode applications

摘要

Transition metal chalcogenides have garnered wide attention of the researchers in energy storage and conversion domains owing to their superior electronic conductivity, mechanical and thermal constancy. Zinc Sulfide (ZnS) has been identified as one of the most important II-VI semiconductor, with a band gap of 3.5-3.8 eV. Excellent ion accessibility and charge storage ability of nanosized ZnS makes this a prospective material in the field of energy storage. Besides ZnS nanoparticle possess advantages such as good electric conductivity, low diffusion resistance, fast electron transportation, non-toxic nature etc. It is a lightweight and cost effective material compared to other metal sulfides. Reports are available on supercapacitor electrodes based on different types of ZnS nanocomposites. However, investigation on the variation of this material's energy storage efficiency with metal doping and increased particle size are comparatively less. ZnS particles with microsphere morphology show enhanced reversibility due to less self-aggregation and volume expansion. In this work we report the synthesis and electrochemical studies of pure & nickel (Ni) doped ZnS microspheres. The synthesis of pure and Ni doped ZnS microspheres were carried out by hydrothermal method. The crystal structure, phase composition, and microstructure of the samples were analyzed by X-ray diffractometer (XRD) and Field Emission Scanning Electron Microscope (FESEM) respectively. The electrochemical behavior of pure ZnS and Ni doped ZnS microspheres were examined by means of Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, and Galvanostatic charge-discharge. At 5A g~(-1) current density, Ni doped ZnS microspheres exhibited an enhanced specific capacitance of 104.2 F g~(-1) where pure ZnS microspheres showed 67.75F g~(-1).