Ni–Zn binary system hydroxide, oxide and sulfide materials: synthesis and high supercapacitor performance†
Abstract
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 ∼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, 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.