The Study Of Electrochemical Capacitance Based On Carbon Material And Its Composites

Supercapacitor has been widely used in electric vehicles, aviation and so on, since it has advantages, such as high power density, high energy density and long cycle life. For a super capacitor, the electrode material will directly determines its electrochemical performance. Therefore, it is the key to explore and develop new electrode materials and new methods to prepare them. In this paper, We took the N-methylpyrrolidone as the precursor of carbon materials. Finally, the carbon microspheres and nanospheres were prepared by electrochemical method. And then the MnO2/C composites and C was prepared in the potassium permanganate solution. The study of electrochemical capacitance based on these materials was also given. The specific contents are as follows:(1) Preparation of carbon microspheres:N-methylpyrrolidone was taken as the precursor of carbon materials and mixed with a certain amount of deionized water, which works as the electrolyte. A polished copper works as the cathode, on which carbon microspheres are finally obtained. The influences of carbon source concentration, deposition voltage and deposition time on the morphology and composition of the products were studied by SEM and Raman. FTIR, XRD and TEM were also used to analyze the composition, morphology and structure of the electrode materials. These results show that the prepared materials are carbon microspheres composed of amorphous carbon and nanospheres with an "onion" structure. The TG report also shows that this material contains some oxygen functional groups and other impurities and the carbon content is about 70wt%. The electrode material showed good electrochemical performance after a heat treatment at 900 ℃ under the protection of N;, and the specific capacitance was 122.4F/g when the scan rate was 5mV7s. With a current density of 1 A/g, the specific capacitance is 102.4F/g.(2) Preparation of MnO2/C composite:MnO2/C composite was prepared by the reduction of KMnO4, triggered by the self-made carbon microsphere powder. The surface of carbon microspheres was embedded by nano particles of MnO2, which helped the produce MnO2/C composite, with a shape of "sesame ball". A study on the influence of reaction time on the morphology and structure of the product was taken on, by SEM and Raman. TG, FTIR, XRD and TEM were also used to analyze the morphology and composition of the electrode materials. The electrochemical performance of the electrodes was investigated. And the results showed that the electrode material of the MnO2/C composite had a good capacity. The specific capacitance was 145.5F/g when the scan rate was 5mV/s. With a current density of 1A/g, the specific capacitance is 128.3F/g.