| As a novel energy storage device, supercapacitor has attracted much attention in recent years. Electrode material is the core of supercapacitor, and it is a hot spot for researchers. In this thesis, we reported the preparation different shape of PANI, and a series of hierarchical porous and N-doped carbon materials are prepared by using PANI as a carbon precursor, and test as electrode material of supercapacitor. This thesis mainly contains the following contents:1. Open carbon nanotube materials with hierarchical porosity and N-doping are prepared from polyaniline nanotubes via a combination method of pre-carbonization and post-KOH activation, and study the multilevel holes and surface functional groups on capacitance performance of activated carbon. The morphology, pore texture and surface properties of the carbon materials are investigated by N2 adsorption, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) and so on. Characterization results reveal that the KOH-activated carbon nanotubes(HPCT-x) have lots of ultra-micropores with the size less than 1.5 nm. The micropores in the tube wall, especially the ultramicropores(<1 nm), could provide a high effective surface area up to 3253 m2·g-1. At the same time, the reversible redox reactions of the heteroatom-doped species induce an extra pseudo-capacitance improving the specific capacitance. The doping of heteroatoms also increases the hydrophilicity and polarity of carbon materials and thus facilitates the wettability between the electrolyte and pore surface. When the hierarchical porous carbon materials were used as the electrode materials for supercapacitors in KOH solution, they exhibit very high specific capacitance, good power capability and excellent cyclic stability. In conclusion, HPCT-4 carbon shows the capacitance of 365.9 F·g-1 at a current density of 0.1 A·g-1, and a high energy density of 10.3 W h·kg-1 at a power density of 45 W·kg-!. This good capacitive performance could be attributed to the synergistic effect of the heteroatomdoping and the hierarchical porosity.2. In this work, we prepared PANI nanoparticles in the presence of poly(4-styrenesulfonate)(PSS) and (NH4)2S2O8(APS). Using the PANI nanoparticles as carbon precursor, activated N-doped carbon nanoparticles(APCNs) are prepared via a combined of pre-carbonization and post-activation. The post-chemical activation step with KOH was used to increase the microporousnetwork. The BET surface area of the APCNs are 639-2456 m2·g-1. The morphology, structure and surface property evolution in the preparation of APCNs are investigated intensively by a variety of means such as, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and N2 adsorption. Characterization results reveal that the good capacitive performance could be due to the synergistic effect of the hierarchical porosity, short micropore length, high effective surface area and heteroatom doping effects. Micropore with short diffusion length due to the small size of nanoparticles and increasing the density of charge storage, nitrogen incorporation leads to additional pseudocapacitance and hydrophilic surface properties adapted to the KOH electrolyte. At a current density 0.1 A·g-1 the specific capacitance of APCN-2 is 331 F·g-1 and at 40 A·g-1 the specific capacitance is 164 F·g-1 in 6 mol9L-1 KOH electrolytes. This carbon shows an excellent characteristic of recycling charge/discharge performance after 10000 cycles, about 96.6% of the discharge capacitance of the initial cycle. The energy density of APCN-2 could be up to 5.7 Wh·kg-1, at a very high power density 10000 W·kg-1. |
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