Fabrication And Characterization Of Polyaniline Coated Electrospun Carbon Nanofiber Composite Materials For Supercapacitors

In recent years, due to the fast and tremendous energy consumption, new devices ofenergy storage and transfer have attracted great attentions of many research workers.Supercapacitor is one of the famous devices in energy storage. An ideal supercapacitor hasfast charging and discharging rate, high power density, extremely long life, good cyclestability and sustainable development with environment. The electrode materials play a keyrole in the supercapacitors and many researches have been developed for preparingsupercapacitor electrode materials with excellent properties.Carbon nanofibers (CNFs) have many advantages such as low cost, non-toxic, highelectrical conductivity and environmental stability. However, the storage mechanism ofCNFs limits specific capacitance. Polyaniline (PANI) is one of the most promisingmaterials for faradaic pseudocapacitors owing to its low price of raw materials, non-toxic,and easiness of preparation. However, the cycle stability of PANI is poor. In thisdissertation, PANI/CNFs via electrospinning and hydrothermal synthesis were proposedfor electrode materials of supercapacitors to enhance their energy storage by synergisticeffect between CNFs and PANI nanoparticles.CNFs is obtained by electrospinning and heat-treatment processing. PANI/CNFscomposite nanofibers were obtained by hydrothermal synthesis using CNFs as templates.The products were characterized by X-ray diffraction (XRD), scanning electronmicroscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy(FT-IR), and X-ray photoelectron spectroscopy. The electrochemical energy storageproperties of the products were investigated via cyclic voltammograms (CV) and constantcurrent charge and discharge (CD) by measurement performed on a CHI660delectrochemical working station. After hydrothermal synthesis, PANI nanoparticles wereuniformly coated on CNFs. The electrochemical performances of PANI/CNFs were muchenhanced due to the synergistic effect of CNFs and PANI. Although the specificcapacitance of PANI is a little larger than that that of PANI/CNFs at low scan rates, afaster decay of specific capacitances with increasing scan rates were observed. Therefore,the specific capacitances of PANI/CNFs were much larger than that of PANI at scan rateslarger than20mVs-1. The capacitance performances of PANI/CNFs were much better thanthat of PANI. The investigation on constant current charge and discharge investigation alsoshowed that PANI/CNFs had larger specific capacitance at discharge current larger than5A/g. The above results showed that PANI/CNFs might have potential applications for supercapacitors with high energy and power densities.