Hierarchical ternary Zn-Ni-Co sulfide/oxide heterostructure for high specific energy hybrid supercapacitor

Abstract

The structure design and composite of electrode materials have positive effect on supercapacitors (SCs) and have become a research hotpot. In this work, a ternary Zn-Ni-Co-S (ZNCS)/Zn-Ni-Co-O (ZNCO) composite is prepared by hydrothermal vulcanization ZNCO for SCs. Especially, a dissolution and recrystallinity process of ZNCO controlled by appropriate vulcanization has a critical role in obtaining such unique structure. The obtained hierarchical ZNCS/ZNCO microsphere with flower-like shape presents large specific area, uniform mesoporous distribution and good conductivity. Moreover, the potential synergistic effect of multi metal ions can provide abundant sites for reversible redox reactions. As expect, the resultant ZNCS/ZNCO composite presents a battery like energy storage kinetics with a specific capacity of 1445 C/g at 1 A/g. For practical purpose, the assembled ZNCS/ZNCO//AC HSC device achieves long lifespan of 93.3% for 20,000 cycles at 7 A/g with a specific energy of 67.05 Wh/kg at 850 W/kg.