石墨因其高導電性以及良好的電化學穩定度，直至今日仍作為主流儲能材料開發的首要選擇。然而由於天然石墨經大量開採其資源終將耗盡，且傳統的石墨化方法仍存在著許多缺點，包含極高的製程溫度、碳前驅物的諸多限制、繁雜的化學處理，以及大量排放溫室氣體等等，因此人們近幾年正著力於研發簡易、環保且高效率將非晶碳黑轉化為高結晶性的人造石墨之方法。於此研究中，我們成功將由廢棄輪胎取得的碳黑，利用熔融鹽電化學法達到石墨化形成奈米片狀石墨。此方法不僅低耗能低汙染，更具有工業化規模發展的潛力。再加上藉由從廢棄輪胎回收碳黑，來實現循環經濟並達到產品高價值化的目標。此外，我們結合催化石墨化的原理，透過直接添加氧化鐵於非晶碳黑中進行電化學法，於低溫下進一步提高碳的石墨化程度以及石墨化均一性。最後，我們將石墨化碳直接作為導電劑應用於鋰離子電池的矽負極。相較於原始的輪胎非晶碳，石墨化碳的導電片狀結構，可改善矽在充放電時電極結構不穩且導電度差的缺點，使得電池的循環表現有顯著提升，並可與商業化導電劑相比擬。此研究不僅提供了廢棄輪胎碳另一高價值化的應用，藉由石墨化時催化劑的添加，更證實了大規模生產與高均一性石墨化同時並進的可行性。

Graphite, because of its excellent conductivity and electrochemical stability, is still the mainstream option for the development of energy storage materials nowadays. Recently, people have been searching for significantly efficient and facile approaches for the conversion of amorphous carbon black into high crystallinity graphitic carbon. However, the traditional graphitization strategies remain problems to be solved, including extremely high operating temperature, restrictions on types of amorphous carbon, complex pretreatment-requirement, and emission of toxic or greenhouse gases such as SO2 and CO2.

In this work, it is demonstrated that graphitic carbon with high degree of graphitization and nanoflake structure is successfully transformed from the hard carbon of recycling waste tire. First, after the pyrolysis and simple pre-acid treatment, pure amorphous carbon black with a porous structure could be obtained. In the next step, the carbon black was converted into highly graphitic structure at low temperature (850 °C), through a facile electrochemical route in molten salt, which is eco-friendly and of high potential for large scale graphitization compared with conventional incineration method. In addition, we further increase the crystallinity and uniformity of product simultaneously by directly mixing the metal oxide catalyst Fe2O3 with carbon precursor. Moreover, the mechanism of metal-catalyzed electrochemical graphitization process has been discussed in detail. To enhance the value of applications, the as-prepared graphitized nanoflakes were used as conductive additives for silicon anodes in lithium-ion batteries, which shows a comparable stability performance as utilizing commercial Super-P additives. It exhibited an initial Coulombic efficiency of around 79.7 % and high capacity retention about 45.8 % after 100 cycles, with reversible capacity of 1220 mAh/g at a current rate of 400 mA/g. Overall, utilizing the low temperature Fe2O3-catalyzed electrochemical process, we successfully recycle waste tires and propose a sustainable but also value-added application in the field of energy storage.

Abstract I
摘要 III
Acknowledgements IV
Table of Contents VI
List of Figures IX
List of Tables XVI
Chapter 1 Introduction 1
1.1 Introduction of waste tire recycling 1
1.1.1 Potential application of waste tire after pyrolysis process 1
1.1.2 Tire-derived carbon as the source of energy storage materials 4
1.2 Introduction of graphite 8
1.2.1 The characteristics of graphite 9
1.2.2 The synthesis of artificial graphite − Graphitization process 11
1.2.2.1 High-temperature treatment for graphitization 12
1.2.2.2 Catalytic graphitization 16
1.3 Lithium ion battery 20
1.3.1 Lithium ion battery overview 20
1.3.2 Working mechanism of lithium ion battery 22
1.3.3 Si-based material as the anode of lithium ion battery 23
1.3.4 Graphite additives for Si-based anode of lithium ion battery 27
Chapter 2 Motivation 30
2.1 Scalable & facile process for graphitization 30
2.2 High value-added applications of tire derived-carbon 30
Chapter 3 Material analysis method and technology 31
3.1 Scanning electron microscopy (SEM) 31
3.2 High-resolution transmission electron microscopy (HR-TEM) 32
3.3 X-ray photoelectron spectroscopy (XPS) 33
3.4 Powder X-ray diffraction (XRD) 34
3.5 Raman spectroscopy 35
3.6 Potentiostat 37
3.7 Coin-cell testing system 37
3.8 Cyclic voltammetry 38
Chapter 4 Results and discussion 40
4.1 Waste tire carbon black acid treatment 40
4.2 Graphitization of pure waste tire-derived carbon by FFC Cambridge method 42
4.2.1 Experimental design 42
4.2.2 Material characterization: Different molten salts as electrolyte 45
4.2.3 Material characterization: Different applied voltages & temperatures 50
4.3 Graphitization of waste tire-derived carbon with Fe2O3 as catalyst 55
4.3.1 Experimental design 55
4.3.2 Material characterization: Different wt.% of Fe2O3 56
4.3.3 Uniformity of graphitized carbon 59
4.4 TEM characterization & mechanism discussion 61
4.5 Battery and electrochemical performance 68
Chapter 5 Conclusions and future works 73
References 75

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