| Electrochemical capacitors ?ECs?, as one of the novel energy storage devices, have been widely used in various fields, due to their high power and energy desity, environmental friendly features and long-term cycle stability. However, the performance of the ECs is influenced by many factors, such as electrolytes, membrane materials and electrode materials etc. Electrode materials, as the key part of the ECs, have an important influence on the capacitance performace. Therefore, the development of new types of electrode materials with high specific capacitance, excellent power characteristics and long cycle life is an effective way to improve the performance of the supercapacitor. In this thesis, in order to prepare new electrode materials with high specific capacitance, excellent power characteristics and long cycle life, porous carbon materials have been synthesized by different methods. The morphologies, structures and capacitance performance of the target materials were investigated by different characterization techniques and electrochemical methods. The main points of this thesis are summarized as follows:?1? Nitrogen-doped porous carbon micropolyhedra ?N-PCMPs? were successfully prepared by direct carbonization of ZIF-11 polyhedra and further activated with fused KOH to obtain N-PCMPs-A. The morphology and microstructure of samples were examined by scanning electron microscopy, X-ray diffraction, and micropore and chemisorption analyzer. Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge method in 1.0 M H2SO4 aqueous solution on a standard three-electrode system. Results show that, compared with N-PCMPs, N-PCMPs-A has higher specific surface area (2188 m2 g-1) and exhibits improved electrochemical capacitive properties (307 F g-1 at 1 A g-1). The mass specific capacitance of N-PCMPs-A is also higher than that of most MOF-derived carbons, some carbide-derived carbons and carbon aerogel-derived carbons. In addition, the capacitance of the N-PCMPs-A retains 90% after 4000 cycles even at a high current density of 10 A g-1. These imply that N-PCMPs-A is the promising materials for the construction of a high-performance supercapacitor.?2? Taking phenylboronic acid as a boron source and ZIF-11 as a carbon template, boron and nitrogen codoped porous carbon polyhedra ?BN-PCPs? were prepared through a simple procedure for the first time. The as-prepared BN-PCPs were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and typical electrochemical methods. The results show that the developed BN-PCPs possess 10.68 atom% B and 8.10 atom% N with uniform distribution, and excellent electrochemical capacitive properties with high specific capacitance of 262 F g-1 at 20 mV s-1 in 1.0 M H2SO4 aqueous solution and excellent long-term charge-discharge stability (no obvious degradation during 40000 charge-discharge cycles at 20 A g-1).?3? Choosing ZnO nanorods as the templates, the ZIF-8 was grown on the surface of the ZnO nanorods in the 2-methyl imidazole solution by the nuclear principle of ZIF-8. Then, the hollow carbon nanotubes ?HCNTs? were prepared by the low temperature carbonization and acid-etching process. Finally, the HCNTs were carbonized by the further high temperature and activated by the fused KOH to get the 3D hierarchical porous carbon ?3D-HPC?. The as-prepared 3D-HPC was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and typical electrochemical methods.3D-HPC has higher specific surface area (1889 m2 g-1) and excellent electrochemical capacitive properties with high specific capacitance of 217 Fg-1 at 20 mV s-1 in 1.0 M H2SO4 aqueous solution and excellent long-term charge-discharge stability (the capacitance of the 3D-HPC retains 94% after 10000 charge-discharge cycles at 20 Ag-1). |
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