Homogeneous precipitation of α-phase Co–Ni hydroxides hexagonal platelets

This paper describes the synthesis of α-phase Co–Ni hydroxides hexagonal platelets through homogeneous precipitation, using hexamethylenetetramine (HMT) or urea as a hydrolytic agent. In the CoCl2–NiCl2–HMT system, pure α-phase can be synthesized at the concentrations of both metal ions higher than 20 mM, while in the CoCl2–NiCl2–urea system, the formation of pure α-phase is independent of the concentrations of the metal ions. When using HMT, monodisperse hexagonal platelets of α-phase Co–Ni hydroxides can be produced in the presence of polyvinylpyrrolidone (PVP). Cyclic voltammogram curve of the hexagonal platelets prepared with HMT demonstrates electrochemical performance superior to that of urea.