Study On The Conductive Additive Of Supercapacitor

Among all the energy storage devices, supercapacitor is becoming a hot topic for thelong life, high energy and other good performances in recent years. The power density isabout ten times than the secondary battery and the energy density is about ten times thanthe electrostatic capacity. The combination of supercapacitors and secondary batteriesform the hybrid energy system which meet the situation of starting up, acceleration andother energy outputing occasions.The system is also designed for energy cycling system.Some appropriate products have been used in the electric vehicle industry in developedcountries and some researches are starting up in our country.An ? type acicular manganese dioxide(MnO2) of nano particles had been fabricatedvia the method of water bath which found the effect of different processes. Thereenhanced the conductivity and specific capacity through electrochemical tests by addingdifferent proportions of acetylene black (AB) or Multi-walled carbonnanotubes(MWCNTs) with MnO2as conductive additive, while he performance got agreat progress in cycling life with the composites of graphene oxide(GO). Themorphology and structure of materials were systematically characterized by scanningelectron microscope(SEM), X-ray diffraction(XRD) and transmission electronmicroscope (TEM). The electrochemical properties of these electrode materials wereevaluated by cyclic voltammetry (CV), galvanostatic charge-discharge(GCD), andelectrochemical impedance spectra (EIS).MnO2particles that prepared dispersed evenly as nanoscale,40nm in diameter and1micron in length. There put15%carbon materials as conductive additive to buildconductive network. The electrode with5%CNT and10%AB had high specific capacityof83.5F/g at0.25A/g and remaind78.3%capacitance retention over1000cycles. Thisgroup had a low resistance and good capacitance performance than the group of15%ABthrough the modeling of ZIVIEW software. The research captured the failure of electrodeby excessive adsorption of ion which the theory could be used in other groups. Theelectrode with15%MWCNTs had only20cycling life in the test. GO had been fabricatedvia the improved method of Hummers. The specific capacity had a little decline at73.65F/g (0.25A/g) after adding GO because of adsorption of high specific area. However, GOshowed a good cycling performance that remaind87.1%capacitance retention over1000cycles which had a certain coating effect on active materials of electrode. Finally, thecompetition effect between resistance and absorption is proofed to be existed through the comparison of properties of materials and the extreme value is between them.