| Supercapacitor is a new type of power devices that occupies a higher energy density than capacitors and higher power density than batteries.The electrode materials are supposed to be the most important part in influencing the performances of supercapacitor. Owning to the simple preparation process, low cost, high capacitance and environment friendly, conducting polymers have been investigated intensively in recent decades. Traditional chemical oxidation and electrochemical synthesis of conductive polymer materials are restricted by its large-scale production and the fact that the preparing process is usually affected by many factors and, thus, limits its applications.In this work, interfacial synthesis route and microemulsion method were employed to prepare a series of conducting polymers. The morphologies, structures and electrochemical properties were investigated and the main contents of this work are as follows:(1) An organic/aqueous interfacial reaction system was used for the preparation of different morphology of PPy samples by varying CTAB in aqueous phase. The electrochemical performance of as prepared PPy was evaluated as electrode materials for electrochemical capacitor,and it was shown that the ultralong interconnected PPy nanowire bonded with spherical PPy nanoparticles could be optionally controlled by adjusting the concentration of CTAB in the range of 6.25 ~ 12.5mmol L-1. Compared with other PPy samples, this unique structure of material possessed more ideal capacitance behaviors, showing a higher specific capacitance up to 328.7 F g-1 at current density of 0.3 A g-1,and 75.7% of initial capacitance was retained even after 600 cycles at current density of 1.0 A g-1.(2) Nano-sized PPy was synthesized by employing SDBS/butyl alcohol/hexane/water microemulsion system, and the capacitance performance of as prepared PPy was evaluated as electrode materials in 1.0 mol L-1H2SO4, Na2SO4 and KCl electrolytes, respectively. It was found that as prepared PPy possessed the highest specific capacitance in H2SO4 electrolyte, which was up to 329.0 F g-1 at current density of1.0 A g-1, much higher than that in Na2SO4(156.6 F g-1) and KCl(153.2F g-1) electrolyte. Shown in the long charge-discharge tests, the specific capacitance of PPy obtained at 1.0 A g-1 in H2SO4 electrolyte decreased quickly with cycle numbers, and only 44.4% of the initial capacitance was retained after 500 cycles. However, the specific capacitances of PPy obtained in Na2SO4 and KCl electrolytes remained nearly stable during the whole cycle performances, and the capacitance retentions were 98.1% and 96.7%, respectively.(3) An alternative one-step route was presented for constructing a novel PANI-coated PPy composite in an ingenious triple-phase interface system, where PPy and PANI were prepared in individual non-interference interfaces and, in the middle aqueous phase, smaller PANI particles are uniformly coated on the surface of PPy particles,forming a core-shell structure. The structure of prepared PPy/PANI composite was fully characterized by SEM, TEM, XRD and FTIR. It was shown that the PPy/PANI composite prepared by the ingenious triple-phase interface system and the original morphology of PPy and PANI were preserved. Under the driving force of the interfical thermal energy nanosized PANI particles were uniformly coated on the surface of PPy microspheres, forming a nano/micro structure. The electrochemical tests showed that PPy/PANI composite presented a superior capacitance behavior of 348.5 F g-1in 1.0 mol L-1H2SO4 electrolyte at current density of 1.0 A g-1, which was much higher than that of PPy(145.0 F g-1) and PANI(290.3 F g-1).The structure, size and morphology of the electrode materials on their electrochemical properties were compared, and electrochemical behaviors of the electrode materials in different electrolytes were investigated, providing a broader strategy for the preparation of conducting polymers, the design of the supercapacitors and the selection of the matching electrolytes. |
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