Construction of NiCoZnS materials with controllable morphology for high-performance supercapacitors

Abstract A facile two-step hydrothermal approach with post-sulfurization treatment was put forward to construct the mixed transition metal sulfide (NiCoZnS) with a high electrochemical performance. The different morphologies of NiCoZnS materials were successfully fabricated by adjusted the Ni/Co molar ratio of the NiCoZn(OH)F precursor. Moreover, the in situ phase transformation from the NiCoZn(OH)F phase to Zn 0.76 Co 0.24 S and NiCo 2 S 4 phases and lattice defects via the S 2− ion-exchange were determined by x-ray diffractometer, transmission electron microscopy and x-ray photoelectron spectroscopy techniques, which improved electric conductivity and interfacial active sites of the NiCoZnS, and so promoted the reaction kinetics. Significantly, the urchin-like NiCoZnS 1/1 prepared at the Ni/Co molar ratio of 1.0 exhibited promising electrochemical performances with high capacitance and excellent cycling stability. Furthermore, the asymmetric device (NiCoZnS//AC) using NiCoZnS 1/1 as the positive electrode had excellent supercapacitor performances with an energy density of 57.8 Wh·kg –1 at a power density of 750 W·kg –1 as well as a long cycle life (79.2% capacity retention after 10 000 cycles), indicating the potential application in high-performance supercapacitors.