Effect of preparation conditions on the electrochemical properties of spherical Ni(OH)_2

Spherical nickel hydroxide is used as the active material of the positive electrode in alkaline recharged batteries,it determines the most important properties of the battery. Spherical nickel hydroxide made in China meets less than half of total demand of the Chinese batteries industry. Most of the spherical nickel hydroxide used for high performance MH/Ni batteries is imported because the Chinese one cannot reach the requirements of "fine crystal grain, high density and high-activity". In this thesis, the spherical nickel hydroxide with fine crystal grain high-density and high-activity was prepared with complexation-precipitation method. The effects of the preparation conditions on the electrochemical activity of the products were investigated by means of orthogonal test, comprehensive range analysis on all the used factors. And theirs levels showed that the optimum process parameters of preparation the fine crystal grain high-density and high- activity spherical nickel hydroxide is specified as reaction temperature 60℃, pH value 11.0, stronger stirring intensity, the mole ratio of ammonia and nickel 0.3,desiccation temperature 100℃. Furthermore, the relative influence degree of those technology factors is stirring intensity>pH value>reaction temperature>desiccation temperature>mole ratio of ammonia and nickel. The spherical nickel hydroxide made at those optimum process parameters is characterized as with high bulk density(1.78 g/cm^3), larger specific surface(11.9 m^2/g), higher discharged specific capacity (281 mAh/g), and fine crystal grain (15.8 nm). The full width of half maximum intensity(FWHM) of XRD patterns of samples in (101) lines can reach as high as 0.983°. All of these merits make it completely meet the requirements of spherical nickel hydroxide used for high performance MH/Ni batteries.

Spherical nickel hydroxide is used as the active material of the positive electrode in alkaline recharged batteries,it determines the most important properties of the battery. Spherical nickel hydroxide made in China meets less than half of total demand of the Chinese batteries industry. Most of the spherical nickel hydroxide used for high performance MH/Ni batteries is imported because the Chinese one cannot reach the requirements of “fine crystal grain, high density and highactivity”. In this thesis, tile spherical nickel hydroxide with fine crystal grain high-density and high-activity was prepared with complexation precipitation method. The effects of the preparation conditions on the electrochemical activity of the products were investigated by means of orthogonal test, comprehensive range analysis on all the used factors. And theirs levels showed that the opti mum process parameters of preparation the fine crystal grain high-density and high- activity spherical nickel hydroxide is specified as reaction temperature 60℃, pH value 11.0, stronger stirring intensity, the mole ratio of ammonia and nickel 0. 3,desiccation temperature 100℃. Furthermore, the relative influence degree of those technology factors is stirring intensity〉pH valuc〉reaction temperature〉desiccation temperature〉mole ratio of ammonia and nickel. The spherical nickel hydroxide made at those optimum process parameters is characterized as with high bulk density（1.78 g/cm^3）, larger specific surface（11. 9 m^2/g）, higher discharged specific capacity （281 mAh/g） , and fine crystal grain （15.8 nm）. The full width of half maximum intensity（FWHM） of XRD patterns of samples in （101） lines can reach as high as 0. 983°. All of these merits make it completely meet the requirements of spherical nickel hydroxide used for high performance MH/Ni batteries.