Effects of different Ni(OH)2 precursors on the structure and electrochemical properties of NiOOH

Nickel oxyhydroxide (NiOOH), an active material for alkaline Zn-NiOOH batteries, was synthesized by electrolysis oxidation of different Ni(OH)2 precursors, which were prepared by three methods: polyacrylamide (PAM) assisted two-step drying (PTSD), conventional co-precipitation (CCP), and “controlled crystallization” (CC). The NiOOH samples were characterized and tested using X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) testing, laser particle size analysis, tap-density testing, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and a discharge test. The results demonstrate that the physical and electrochemical properties of NiOOH are strongly dependent on the properties of the Ni(OH)2 precursor, such as its morphology, microstructure, tap density, and specific surface area. The results of the electrochemical studies also show that the sample prepared by the PTSD method is superior to the others in electrochemical performance. The as-prepared, high-density, non-spherical NiOOH is a promising active material for the positive electrode in Zn-NiOOH batteries.