To avoid aggregation in the production of the active electrode material, Ni–Zn system materials (Ni_xZn_1−xOH, NiO–ZnO and Ni_xZn_1−xS) were synthesized by using a belt reaction zone model, and then were characterized systematically in this work. Among these materials, Ni_xZn_1−xS porous spheroid nanoparticles with diameters ∼30 nm possess abundant interconnected micropores caused by the Kirkendall effect in the synthesis, leading to a high surface area of 148.4 m² g⁻¹ and special paths for ion diffusion. In the three-electrode system testing, Ni_xZn_1−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 Ni_xZn_1−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.