Effect of preparation conditions on properties of Al-substituted α-Ni(OH)2 prepared by homogeneous precipitation

Al-substituted α-Ni（OH）2 was synthesized under different reaction conditions by a homogeneous precipitation method. The effect of reaction temperature, reaction time, Ni and Al ions concentration and reagent ratio on the physico-chemical properties and electrochemical performance of Al-substituted α-Ni（OH）2 was studied. The Al-substituted α-Ni（OH）2 samples were characterized by X-ray diffractometry（XRD）, infrared spectrometry（FT-IR）, inductively coupled plasma（ICP）, thermogravimetry（TG） and electrochemical test. The results reveal that the physico-chemical properties and electrochemical performance of the sample are influenced strongly by the preparation conditions. Keeping reaction temperature at 100 or 104℃ is appropriate and the largest specific discharge capacity of the sample is 320mA·h/g. With the reaction time increasing, the discharge capacity increases first and then decreases slightly. It is appropriate that the Ni and Al ions concentration and the ratio of urea to Ni and Al ions are 0.42mol/L and 0.75∶1, respectively.