The Preparation And Electrochemical Properties Of Ni?OH?₂ And Composites

Transition metal compound can cause highly reversible redox reactions during as electrode material.The Faraday pseudo-capacitance caused by reversible redox reactions is much higher than double-layer capacitance caused by carbon materials ion desorption and adsorption. Nickel-based compounds become research focus in the field of electrochemical electrode materials because of their thermostability, chemical stability and high theoretical specific capacity.In this thesis, a hydrothermal synthesis method is adopted to prepare Nickel hydroxide and Ni?OH?₂/ITO composite electrode material by changing precipitators. The microstructure and morphology were characterized by XRD, SEM, HRTEM, FT-IR, XPS and other characterization methods; The electrochemical properties were characterized through current density charge-discharge, Cyclic Voltammetry ?CV? and AC impedance, the results of the study are as follows:Nickel hydroxide prepared by hydrothermal method, urea as precipitant, AC^-18 as additive, nickel hydroxide with different crystal type prepared through different process conditions. The sample prepared at 180? for 1 hour has flower ball structure with good crystalline, and the specific capacitance is 1526.62 F·g^-1 at a current density of 0.1A·g^-1, and still remain 76% of the initial specific capacitance after 10000 cycles, which is much higher than the other samples prepared with different conditions. Nickel-based compounds with different composition and morphology were prepared by changing the types of precipitants. The experimental results show that:the sample added AC^-18 increase the contact of electrode materials and electrolyte, makes the constraint capacitance reaction more thoroughly because of its unique three-dimensional layered structure; The addition of AC^-18 can promote the formation of the 3 D flower spheres; The sample prepared with CS?NH2?₂ as precipitant also has excellent electrochemical performance:the specific capacitance of the sample is 825.12 F·g^-1 at the current density of 0.1A·g^-1, in addition, the impedance value is small; With sodium hydroxide as precipitant,180? reaction 1 hour for particle size of sample for 30-80 nm hexagonal lamellar structure of ?-Ni?OH?₂ particles, the specific capacitance is 993.6 F·g^-1 at a current density of 0.1A·g^-1, and the specific capacitance decreased with the increase of current density fast. Ni?OH?₂/ITO composite electrode material has been prepared through hydrothermal method, urea as precipitant, Ni?OH?₂/ITO series of different mass ratio of composite electrode materials were made at 180? for 2 hours, and research the mix of ITO influence on electrochemical properties. When the mass ratio is 0.1 of ITO and Ni?OH?₂, the specific capacitance is 1160.64 F·g^-1 at the current density of 0.1A·g^-1, the performance of composite electrode materials with this ratio of electric is best. Therefore, adding suitable amount of ITO can effectively reduce the internal resistance of the material, and improve the electrical conductivity of the composite materials.