Preparation of nanosphere-interspersed flower-like heterostructure of ZnS/ZnCo2S4@Ni(OH)2 and its application for asymmetric solid-state supercapacitor

Poor conductivity and easy aggregation of the two-dimensional Ni(OH)2 astrict their extensive applications in supercapacitors. In the current study, a nanosphere-interspersed flower-like heterostructure of ZnS/ZnCo2S4@Ni(OH)2 is successfully synthesized by exploiting high conductivity of ZnS/ZnCo2S4 nanosphere which are gown on the ultra-thin sheets of Ni(OH)2 via a solvothermal reaction. ZnS/ZnCo2S4@Ni(OH)2 electrode delivers a remarkable specific capacitance of 2276.9 F/g at 1 A/g, a considerable high-rate capability (1327.5 F/g at 15 A/g), and an excellent cycling stability (retention of 90.4 % at 15 A/g after 5000 cycles). The all-solid-state hybrid supercapacitor (HSC) device is constructed using ZnS/ZnCo2S4@Ni(OH)2 and active carbon as positive and negative electrode active material, respectively. Imposingly, the device manifests high operating potential of 1.6 V, large energy density of 61.4 Wh/kg at power density of 1.0 kW/kg, as well as good stability of 94.5 % retention after 10,000 cycles. This study provides insight into electro-active materials design and construction of heterostructures for high-performance supercapacitors.