Abstract:The high density nano-crystalline multiphase nickel hydroxide containing at least three doping elements was synthesized and its electrochemical characteristics were studied. The electrochemical behavior of the high density spherical multiphases α-Ni(OH)2 were also investigated. The results show that the structure of the material is a mixed phase of α-Ni(OH)2 and b-Ni(OH)2, which has a the same stabilized structure as α-Ni(OH)2 during long-term charge/discharge process. High density spherical multiphases α-Ni(OH)2 have a much better redox reversibility, a much lower oxidation potential of Ni(Ⅱ) than the corresponding oxidation state in the case of b-Ni(OH)2, and a much higher reduction potential. They exchange one electron during electrochemical reaction and have a higher proton diffusion coefficient. The mechanism of the electrode reaction is proton diffusion, and the proton diffusion coefficient is 5.67´10−10 cm2/s. Moreover, they reveal a higher discharge capacity than b-Ni(OH)2/b-NiOOH because they exchange one electron per nickel atom during charge/discharge process.

Key words: multiphase nickel hydroxide; electrochemical performance; voltammogram; exchange electron number; manganese