Preparation, Carbon Compound And Capacitance Performance Of Polyaniline

Polyaniline(PANI) as the most important conductive polymer,has received wide attention for researchers domestic and oversea. In particular, study on PANI/carbon composites has become one of the hotspots of its applied investigation. In this paper,PANI and its composites with carbon nanotubes(CNTs) as electrochemical capacitor electrode materials are proposed. The structure and morphology of the products were characterized by(Scanning electron microscope) SEM,(Brunauer-Emmett-Teller)BET, X-ray diffraction(XRD), Infrared spectra(IR) and Transmission electron microscopy(TEM). The electrochemical capacitance performance of the products was estimated by cyclic voltammetry(CV), galvanostatic charge/discharge(CD) and electrochemical impedance spectroscopy(EIS) techniques. The morphology,nanostructure, preparation and electrochemical capacitance performance of PANI and its composites with CNTs were studied systematically.The preface outlines the structures, Principles and Applications of ultracapacitors,and describes the structure, conductive mechanism and preparation method of PANI.Finally, the research and application prospects of PANI and its carbon composite materials as supercapacitor electrodes are elaborated.Superfine shuttle-shaped polyaniline(PANI) nanoflowers with radiating whiskers at the edge of the flowers have been synthesized using a block copolymer-assisted reverse microemulsion system. The copolymer poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide)(P123) served as the surfactant stabilizing reverse micelles. The correlation between some important factors(polymerization method, P123 and aniline concentrations, and reaction time)and the morphology was discusse. The flowers formed had widths of ca. 40~150 nm and lengths of ca. 80~180 nm. More importantly, the unique architecture showed good electrochemical properties with a high reversible capacitance(622 F g-1at 0.5 A g-1, and 484 F g-1 at 2 A g-1) and good durability(76% capacitance retention at 5 A g-1after 1000 cycles) due to the nano size and V-type channels. These characteristics make it promising for supercapacitor applications.Porous carbon-based hybrids consisting of nanoscale building units are highlighted as supercapacitive materials for outstanding rate capability and cyclability.Herein reported are new hierarchically porous core-shell hybrids of polyaniline@carbon nanotube(PANI@CNT) with ultrafine nanofiber-assembled network shell for supercapacitors via a facile and reproducible reverse microemulsion polymerization route. The hybrids offer high specific capacitances up to 613 F g-1at0.5 A g-1 with good capacitance retention of about 84% at 2 A g-1 in contrast to pristine PANI(526 F g–1 with 76% retention). Moreover, 80% of initial capacitance still remains over 1000 cycles at 5 A g-1. The data clearly reveal a dramatic improvement of the hybrids in performance containing capacitance and rate capability meanwhile lifetime, thanks to unique structure features with highly surface-porous PANI nanofiber networks intimately wrapped around conductive CNTs helping to greatly promote faradic redox process and cycling behavior.Finally, the approach for PANI and its composites with more order structures was explored. Urchin-like polyaniline microspheres and three dimensional three-dimensional core-shell PANI/CNT composites were prepared by solution polymerization under low temperature using sulfuric acid as the dopant. At a current density of 0.5 A g-1,specific capacitances of pure PANI and PANI/CNT composite electrodes were 670 and 772 F g-1 respectively. At a current density of 5 A g-1,the capacitance retention rate of PANI/CNT composite was 80% after 1000charge/discharge cycles. Especially the PANI/CNT composites with high specific capacitance, good rate characteristic and great durability, are expected to be applied to the supercapacitors.