Ni-Zn binary system hydroxide, oxide and sulfide materials: synthesis and high supercapacitor performance

To avoid aggregation in the production of the active electrode material, Ni-Zn system materials (NixZn1-xOH, NiO-ZnO and NixZn1-xS) were synthesized by using a belt reaction zone model, and then were characterized systematically in this work. Among these materials, NixZn1-xS porous spheroid nanoparticles with diameters similar to 30 nm possess abundant interconnected micropores caused by the Kirkendall effect in the synthesis, leading to a high surface area of 148.4 m(2) g(-1) and special paths for ion diffusion. In the three-electrode system testing, NixZn1-xS porous spheroid nanoparticles show the highest specific capacitance of 1867 F g(-1) at a current density of 1 A g(-1), as well as excellent rate capability and cycling stability. Using NixZn1-xS as the positive electrode and active carbon as the negative electrode, the asymmetric supercapacitor device exhibits an excellent electrochemical performance. The results provide us with a modified method to synthesize metal hydroxides, oxides and sulfides, in order to obtain materials with high supercapacitor performance.