Synthesis And Electrochemical Properties Of Nickel Oxide And Its Composite Materials For Supercapacitor

Supercapacitors have been recognized as unique energy storage devices which have higher energy density than conventional capacitors, and higher power density and longer cycle life than batteries, filling the gap between conventional dielectric capacitors and batteries. They can release large discharge current instantly. Based on the above, the promising application of supercapacitors in the fields such as mobile telecommunication, information technology, consumer electronics, electric vehicle, aviation&aerospace, and military force, have been attracting more and more attention throughout the world. Now supercapacitors have become a hotspot in research, and in many countries other than China, supercapacitors have been successfully used in electric vehicles. There isn't any report on applicable supercapacitors techniques or products in our country. For all purposes, it's very important to have study on supercapacitors for the promotion of electric vehicles in our nation. We prepared a series of nickel oxide (NiO) and its composites materials using chemical precipitation method. We used the aids of the measure methods such as X-rays diffraction (XRD), scan electronic microscope (SEM), cyclic voltammetric measurements (CV), constant charge/discharge measurements, Ac-impedance, Thermogravimetric Analyzer (TGA) and so on to examine the products. By experiments we got the conclusions as follows: NiO and NiO/acetylene black (AB) composite materials were prepared by thermal decomposition of the precursor obtained via a simple chemical precipitation usingβ-cyclodextrin (β-CD) as soft template. We found that the addition of AB can enhance the electricity, cycle reversibility and specific capacitance of NiO. And useβ-CD as soft template can improve the cycle reversibility and specific capacitance further, the specific capacitance of 240 F·g-1 was obtained for as-prepared composite materials, and the CV curves approach to rectangle. This is a new progress compared to the literature reports.NiO/expanded graphite (EG) composite materials were prepared by chemical precipitation method. We studied the effect of different thermal treatment method on the materials. It can be found from examinations that the composite material obtained by second expanded had better properties. It has smaller grain diameter, larger specific surface and better electrochemical performance. The max specific capacitance is 160 F·g-1, increasing 39.1% compared to the composite without further expanded.NiO was synthesized by chemical precipitation using nano silicon dioxide (SiO2) as carrier. The grain diameter is bigger than the former two materials. It is micron grade and the others are nano grade. The grains distribute uniformly and the specific capacitance is bigger than NiO/EG composite materials. We researched the influence of different addition of SiO2 on final materials. It can be found that the material prepared when the mass ration of SiO2:NiO is 1:1 has better properties. It has smaller grain diameter, distribute uniformly, smaller polarization, has smaller equivalent series resistance and charge transfers resistance. In a word, it suits to be used as supercapacitor electrodes materials.