Study On The Preparation Of Supercapacitive Materials And Their Electrochemical Properties

The aim of this research is to explore the use of cheap raw materials and simple synthetic techniques for preparing high specific capacitance of conducting polymers, nitrogen-enriched carbon materials, mesoporous carbon and mesoporous carbon@conducting polymer composite materials, which were used as the electrode materials of super-capacitors. The obtained materials were analyzed by various characterization methods for its structure and performance. The major contents can be summarized as follows:(1) In this work, polyaniline (PANI) nanowires and polypyrrole (PPy) nanoparticles were synthesized by chemical oxidation polymerization with aniline, pyrrole as monomers and FeCl3 as oxidation. The as-prepared products were characterized by X-ray diffraction analyzer (XRD), Infrared analyzer (FT-IR), Scanning electron microscope (SEM) and Transmission electron microscope (TEM). The electrochemical performances of the conducting polymers were characterized by cyclic voltammetry (CV) and galvanostatic charge/discharge curves. The experimental results show that the specific capacitance of the PANI testing under the scan rate of 2 mV s-1 in 1 mol L-1 H2SO4 aqueous solution is up to 451 F g-1. The specific capacitance of the PPy is 288 F g-1. However, cycle life of PANI and PPy is poor.(2) Nitrogen-enriched carbon materials were synthesized by direct carbonization method in N2 atmosphere under different carbonization temperature using the obtained PANI and PPy as carbon sources. The experimental results suggest that a optimum carbonization temperature is 700℃. Nitrogen-enriched carbon materials have an excellent supercapacitive performance and large current charge/discharge performance by cyclic voltammetry, galvanostatic charge/discharge and cycle life test. Under the current density of 0.1 Ag-1, the specific capacitance is up to 327 F g-1, and the capacitance of nitrogen-enriched carbon material retains up to 92.4% at the scan rate of 20 mV s-1 after 5000 cycles, revealing the excellent reversibility of this carbon material.(3) Mesoporous carbon was prepared by simple one-step method using triblock copolymer (F127) as structure directing agent, TEOS as silicon source and sucrose as carbon source. In order to check the structure and morphology of mesoporous carbon materials, the volume proportion of ethanol and water in solvent was discussed. Meanwhile, the morphology and structure of mesoporous carbon materials was characterized by XRD, TEM and BET, and then the electrochemical measurement was carried out at room temperature.(4) The mesoporous carbon materials were employed as the carrier and then mesoporous carbon@polypyrrole composites were synthesized by chemical oxidation polymerization with pyrrole as monomers and FeCl3 as oxidation. The electrochemical results show that composite materials effectively combine electric double layer capacitor of carbon with pseudocapacitor of polypyrrole, significantly being improved the capacitive performance of electrode materials. The specific capacitance of the mesoporous carbon@polypyrrole composite electrode is as high as 313 F g-1via CV measurement, more than that of mesoporous carbon electrode (163 F g-1).