Research On Nickel Hydroxide Cathode Material Nickel Hydroxide

Zinc-nickel battery has the high specific energy,the high specific power and the wide operating temperature range.The open circuit voltage of this battery is 1.73V and this battery can charge with high current.The battery is characterized by abundant raw materials,low cost and environmental friendly.As a new energy green power,this battery has great development and application potential.In this paper,the preparation methods of nickel hydroxide,through access to relevant literature at home and abroad,are described such as liquid phase precipitation method,homogeneous precipitation method,hydrothermal method,oxidation method,high pressure hydrolysis method,ion exchange resin method,microemulsion method,electrolysis method and mechanochemical synthesis method.The effects of the preparation process on the structure,morphology,size and capacity of the prepared nickel hydroxide were described.The effects of adding elements on the structure,capacity and electrochemical properties of nickel hydroxide and the preparation methods of doped nickel hydroxide were reviewed.Meanwhile,the characteristics,structure,working principle,the existing problems and solutions,nickel electrode type and its pressing process of zinc nickel battery were also introduced.The X-ray diffraction(XRD),scanning electron microscopy(SEM),electrochemical impedance spectroscopy(EIS),cyclic voltammetry(CV),polarization curves were used to characterize and test the prepared materials.The optimum technological parameters such as pH,ammonia concentration,reactant concentration and stirring strength were determined when the nickel hydroxide was prepared by liquid phase precipitation method.The optimum pH value of the reaction system was 10.5,and the optimum ammonia concentration was 2mol/L,the best reactant NiSO4 concentration of 1.2 mol/L,stirring strength of 220r/min.Under these conditions,the maximum tap density of nickel hydroxide can reach 1.53g/cm3.The effect of adding Ni(OH)2 seed on the morphology of nickel hydroxide is small,adding Ni(OH)2 seed with appropriate mass fraction of 20%can enhance the compactness of nickel hydroxide particles.And the effects of polyethylene 2000,polyvinylpyrrolidone and cetyltrimethylammonium bromide as surfactants on the morphology and tap density of nickel hydroxide were studied and the most significant of which was polyvinylpyrrolidoneThe spherical nickel hydroxide was prepared by liquid-phase precipitation method under ultrasonic assisted ways.The effect of ultrasonic intensity on the morphology of nickel hydroxide was studied and it was found that the ultrasonic strength had a significant on the surface of nickel hydroxide particles.Besides,?-Ni(OH)2 with size of about 10?m was prepared with the appropriate ultrasonic power intensity 216W.The prepared material was pressed into an electrode for testing.And the results indicated that discharge specific capacity of this material can up to 260 mAh/g under the certain charge and discharge system—the charging at 0.4 C for 3 h,standing 3min and discharging at 1C to 1.2 V.The effect of nickel hydroxide with different amount of cobalt on the internal resistance,polarization,electrode capacity,corrosion resistance and cyclic stability of nickel hydroxide was studied by chemical precipitation.It was found that the spherical nickel hydroxide was able to improve the performance of the electrode after covering the cobalt,and the optimum content of cobalt was 3%.The results showed that the nickel-coated nickel electrode had a cyclic retention rate of 83.2%after 40 cycles under the certain charge and discharge system—the charging at 0.2 C for 6 h,standing 5 min and discharging at 0.2C to 1.2 V.