Zn-BTC MOF as Self-Template to Hierarchical ZnS/NiS2 Heterostructure with Improved Electrochemical Performance for Hybrid Supercapacitor

Abstract

Zn-BTC (H3BTC refers to 1, 3, 5-benzoic acid) MOF was used as a self-template and a zinc source to prepare ZnS/NiS2 with a layered heterogeneous structure as a promising electrode material using cation exchange and solid-phase vulcanization processes. The synergistic effect of the two metal sulfides enhances the application of ZnS/NiS2. And the high specific surface area and abundant active sites further promote the mass/charge transfer and redox reaction kinetics. In the three-electrode system, the specific capacitance was as high as 1547 F/g at a current density of 1 A/g, along with satisfactory rate capability (1214 F/g at 6 A/g) and cycling performance. Coupled with activated carbon (AC), the prepared hybrid device (ZnS/NiS2 as the positive electrode and AC as the negative electrode) (ZnS/NiS2/AC) can be operated under a potential window of 1.6 V and provides a high energy density of 26.3 Wh/kg at a power density of 794 W/kg. Notably, the assembled ZnS/NiS2//AC showed little capacity degradation after 5000 charge/discharge cycles.