近幾十年來，劇烈的氣候變化及有限的化石燃料儲量，使得再生能源以及儲能系統受到很大的關注。再生能源如：風能和太陽能，是地球上相較之下較容易獲得的能源，但由於其間歇性的緣故，使如何更有效率的儲存能量變得更為重要。而在眾多的儲能元件中，超級電容具有高功率密度、快速充放電的能力、高循環壽命等之優點，無論在混合動力汽車、電動車、通訊、記憶體等方面皆有很大的應用價值及潛力。本研究是利用熱化學氣相沉積法在高多孔性之泡沫鎳基板上合成石墨化奈米碳纖維及三維石墨烯之複合結構，並將其應用於超級電容之電極上。本研究之複合結構具有高孔隙及高比表面積，以6 M KOH做為電解液進行電化學量測，在電流密度1 A g-1 下可以得到優異之電容值達59.28 F g-1，藉由長效性的充放電測試，經過了1000個循環，電容值仍然可以維持於90.66 %，表示了此材料優異的長效循環壽命。這些結果顯示了此石墨化奈米碳纖維及三維石墨烯之複合結構具有極佳之潛力成為超級電容之電極，對於儲能元件上之應用有極大的幫助。

In recent decades, the climate change and the limited reserves of fossil fuels, and energy security concerns, have promoted internationally interest in developing renewable energy technologies from renewable and endurable energy resources. In fact, there is a speedy increase in renewable energy productions from wind and solar energy, the most bountiful and easily available resources. Given the intermittent nature of solar and wind energy, efficient energy storage systems are urgently required to make the best of the electricity generated from these sources since they can boost the effective and reliability use of the entire power system by storing energy when in excess while releasing it when in high demand. For this purpose, supercapacitors have been promising candidates for the energy storage requirement. In this study, we reported the synthesis of graphitic nanofibers/three dimensional graphene (GNFs/3D graphene) hybrid nanostructure on highly porous nickel foam via thermal chemical vapor deposition (CVD) process. This hybrid nanostructure demonstrated to possess a large surface area and showed an excellent specific capacitance of 59.28 F g-1 at a current density of 1 A g-1, good cycle stability with capacitance retention of 90.66 % after 1000 cycles in 6 M KOH electrolyte. These results suggested that this hybrid nanostructure is a promising candidate which provides a simple and effective technique to prepare electrodes for supercapacitor.

Table of Content
Abstract i
摘要 ii
致謝 iii
Table of Content v
List of Tables viii
List of Figures ix
Chapter 1 Introduction 1
Chapter 2 Literature Reviews 5
2-1 Basic of supercapacitor 5
2-2 The principle of supercacitor 7
2-2-1 The energy storage mechanism of EDLCs 7
2-2-2 The energy storage mechanism of pseudocapacitors 9
2-3 Basic of carbon nanomaterials 10
2-3-1 The synthesis of carbon nanomaterials 12
2-3-2 Applicaton of carbon nanomaterials for supercapacitor 17
2-3-3 Three dimentional carbon nanomaterials 19
Chapter 3 Experimental details 21
3-1 Fabrication of 3D graphene foams 22
3-2 Synthesize of Nickel nanoparticles on 3D GFs 24
3-3 Synthesize of graphitic nanofibers on 3D GFs 25
3-4 Electrochemical measurements 26
3-5 Characterization and Instruments 28
3-5-1 Thermal CVD system 28
3-5-2 ECD and electrochemical analysis system 29
3-5-3 Raman spectroscopy 30
3-5-4 Field emission scanning electron microscope (FESEM) 31
3-5-5 High-resolution transmission electron microscopy (HRTEM) 32
Chapter 4 Results and discussions 33
4-1 Physical characterization 33
4-1-1 Surface morphology 33
4-1-2 Raman characterization analysis 37
4-2 Electrochemical characterization 39
4-2-1 Cyclic voltammetry 39
4-2-2 Galvanostatic charge-discharge 40
4-2-3 Electrochemical impedance spectra 42
Chapter 5 Conclusions 44
References 45

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