Preparation Of Nickel Hydroxide And Nickel Hydroxyl Oxide And Their Electrochemical Performances

At present, electrochemical capacitor and nickel/mental hydride (Ni/MH) battery are two kinds of important energy storage devices. Electrochemical capacitor is a new type of energy storage devices with the advantages of both electrical double layer that can deliver high power within a very small period and conventional rechargeable batteries that have high energy densities. Therefore, electrochemical capacitors have a wide range of applications and have already become one of the research interests related to new chemical energy sources. At the same time, alkaline rechargeable batteries such as nickel/metal hydride (Ni/MH) are widely enter to today's market covering domains ranging from power tools to portable electronics and electric vehicle. Furthermore, nickel/metal hydride (Ni/MH) batteries are considered to be one of the most promising choices for the power systems of electric vehicle (HEV) due to high power and low cost.In this work, we have prepared several electrode materials of electrochemical capacitor and nickel/mental hydride (Ni/MH) battery, and studied the electrochemical performance, structural and morphological feature of these nanomaterials in detail. The main content is as follows:A sheet-like Mn-dopingα-Ni(OH)₂ was successfully prepared with a chemical coprecipitation method, in which nickel sulfate and manganese(â…¡) sulfate were used as the raw material and polyethylene glycol as the structure-directing agent. The components of products were analyzed by FT-IR and thermogravimetry(TG). The structure and morphology were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The electrochemical performances were investigated by cyclic voltammetry and constant current charge/discharge techniques. The results show that the electrochemical performances of the resultant samples depend significantly on the Mn-doping content. The specific capacity as high as 330 mAh/g is achieved at the Mn-doping amount of 30%, suggesting that the Mn-dopingα-Ni(OH)₂ is a promising positive material for Ni/MH cells.A spherical-like Zn-dopingα-Ni(OH)₂ was successfully prepared with a chemical coprecipitation method, in which nickel nitrate and Zn(â…¡) nitrate were used as the raw material and polyethylene glycol as the dispersant. The components of products were analyzed by FT-IR and thermogravimetry (TG). The structure and morphology were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The electrochemical performances were investigated by cyclic voltammetry and constant current charge/discharge techniques. The results show that the electrochemical performances of the resultant samples depend significantly on the Zn-doping content. The specific capacity as high as 303mAh/g is achieved at the Zn-doping amount of 10%, suggesting that the Zn-dopingα-Ni(OH)₂ is a promising positive material for Ni/MH cells.Aβ-NiOOH was prepared through a chemical oxidation under the optimal reaction conditions. The molar ratio of oxidant is a key factor for obtaining the products with high electrochemical performance. The components of products were analyzed by FT-IR and thermogravimetry (TG). The structure and morphology were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The results indicate that the as-synthesized product isβ-NiOOH with hexagonal structure and small crystal grain. The electrochemical performances were investigated by cyclic voltammetry and constant current charge/discharge techniques. The obtainedβ-NiOOH was testified to exhibits excellent specific capacitance as high as 882F/g when the molar ratio of KMnO4 to K2S2O8 was 1:2, indicating thatβ-NiOOH is a promising electrode material for supercapacitor.