The Research Of Carbon Nanotube Composite Supercapacitor

Supercapacitor is a new energy storage device, it has higher power density andlonger cycle life than batteries, and it also has higher energy density than conventionalcapacitor.Supercapacitor has many advantages, for example, long cycle life, highspecific capacitor, broad using temperature range, large charge/discharge current, greeninitiative, and so on. So it has become the focus of research. Electrode material is thekey to determine its characteristics. In this study, we major to research good electrodematerial for supercapacitor. Carbon nanotubes（CNT） and MnO₂are the two materialswe discuss. We prepared electrode materials by different methods, surveyed theirmorphology and elements. And the specific capacitance（SC） of them were measured atneutral electrolyte at different current density. The main contents and innovative pointsare as follows:1. Discussed the influence of acidification of backflow for CNT, the morphologyand elements of that were by SEM and EDS. Results show that acidification can deletethe impurities within CNT well and open the two ends of CNT. So that both innersuperficial area and outer superficial area of CNT can form double layer capacitor. Thegalvanostatic curves show that the SC of CNT without acidification is78.31F/g, and theSC of CNT after acidized10h is154.25F/g, increase by96.97%;2. Prepared MnO₂nano-particle by liquid coprecipitation and annealed the product.The result of SEM show that the diameter of MnO₂is about200-300nm,the bestannealing condition is800℃/2h.The galvanostatic curves show that the SC of MnO₂nano-particle is113.94F/g,The galvanostatic curves show that the SC of MnO₂afterannealed is about260.09F/g,increase by128.27%;3.MnO₂nano-line was prepared by hydrothermal method at different temperatureand different time,the results show that the best reaction condition is120℃/18h, in thiscondition, the diameter of nano-line is about20-30nm and the length is about1-2μm,The galvanostatic curves show that the SC of MnO₂nano-line is about166.62F/g. Butwhen the reaction temperature grow to140℃, the conduct is stick and SC fall to41.02F/g; 4.Used the CNT after acidized10h as carrier, Manganese dioxide coated carbonnanotubes were prepared by liquid coprecipitation. The result show that the best dopingproportion is20wt%CNT, in this condition, the SC of electrode material is178.89F/g,but the SC of treated CNTs is154.25F/g, the SC of MnO₂nanoparticle withouttreatment is only113.94F/g, it is obvious that the SC of composite increased by16.62%than CNT and58.75%than MnO₂.