The Research On Electrode Material Of Super Capacitor

Super capacitor is a new device of energy storage between a traditional capacitor and battery. Super capacitor has many advantages, such as the high efficiency of charge and discharge, super-large current of releasing instantaneous and long cycling life, etc. It has wide application prospects in mobile communication, information technology, consumer electronics, electric vehicles, aerospace, national defense technology and other areas, which attract great concern in the world.At present, the research of super capacitor is mainly focused on the preparation of high performance electrode materials. The research has become more important on how to improve the capacity of the capacitors and energy density. In the paper, needle coke, active carbon and some metal oxide or their compound is used respectively for the preparation of electrode materials, the activation of nitric acid and the preparation of electrode materials are researched, the method of scanning electron microscope(SEM) is used to represent the surface topography of each electrode sample, X-ray diffraction(XRD) is used to represent the crystal structure and some crystal parameters of them, and IR spectrometry(FT-IR) is used to represent the state of each sample surface, finally, the cyclic voltammetry(CV) and exchange impedance spectroscopy(EIS) is used for the electrochemical test. The main content of this paper is as follows:(1) Many needle coke samples which active different times in nitric acid are used as electrode materials of super capacitor. It is found that the current-voltage features are obvious after the activation of the needle coke. And the capacity is also improved, and the needle coke that active24hours has larger electric capacity than that active3hours. Then, the needle coke samples are prepared in different activation temperature and activation concentration which are used as electrode materials of super capacitor. The consequence is that the layer structure is more apparent when the needle coke is prepared by heating activation and nitric acid concentration of40%, moreover, micro crystal structure tend to complete and surface more oxygen.(2) The activate conditions are activate24hours, heating activation and activation density is40%in the environment of nitric acid, then, the needle coke and activated carbon is compound by equivalent quality. The needle coke, active carbon and the compound is used as super capacitor respectively. Compared to the electrode of needle coke, the capacity of compound materials is improved. Compared to the electrode of activated carbon electrode materials, the double layer characteristics of composite materials electrode is obviously good. From a series of tests, a conclusion can be made that composite material electrode has more advantages than electrode which has a single electrode material, and the composite material electrode can make each single material properties play its full role.(3) Manganese dioxide has been dried for four hours in120℃. After that, it has two or more crystal structure and the size of it is also evener. Then, the manganese dioxide which has been activated is mixed with the composite material of needle coke and activated carbon. After the circulation current-voltage test, oxidation and reduction reaction is more apparent and the capacity is improved when the manganese dioxide is mixed. The test has been shown that the contact area between the electrode material and the electrolyte solution is increased when the composite materials mixed with manganese dioxide, which make full use of the active material. While manganese dioxide is10%in the composite materials, the capacitance of composite electrode is61.8F-g-1, and the capacitance is improved by95%than composite materials that with no mixture. Electrochemical impedance test is shown that the internal spread resistance of electrode materials is the least when doping content is10%, the electrode also has good capacitance characteristics.