Two Step Synthesis of Zns-Nis2 Composite with Rough Nanosphere Morphology for Asymmetric Supercapacitors

Abstract

Transition metal sulfides have excellent electrochemical performance, and show great potential for improving the energy density of asymmetric supercapacitors. Two-step synthesis strategy and increased energy storage performance of ZnS-NiS2 composite materials for asymmetric supercapacitors are demonstrated in this work. In the rough surfaced spherical ZnS-NiS2 composite materials, ZnS nanosheets and NiS2 nanocrystals are composited together, with the optimal ZnS-NiS2 composite ratio sample (ZnS-NiS2-1:7) showing the highest specific capacitance of 1467.9 F/g at 1A/g. When compared with pure NiS2 sample, the specific capacitance of the ZnS-NiS2-1:7 sample is 303.6 F/g (26.1%) higher. Besides, the assembled ZnS-NiS2-1:7//AC device shows a high specific capacitance of 127.8 F/g at 1 A/g and an energy density of 51.3 Wh/kg at a power density of 820.8W/kg. Not only does the ZnS-NiS2-1:7 sample itself have outstanding energy storage performance, it can also be composited with graphene for further specific capacitance improvement (1681.0 F/g at 1 A/g), indicating good future development opportunities of the ZnS-NiS2 based composite material.

Keywords: Nickel disulfide, Zinc sulfide, nanosphere, electrochemical characterization, Asymmetric supercapacitor.