在最近幾十年，由於人口的急劇上升，越來越多的廢棄物被製造出來，也因為人口的增加，使得有限的能源消耗的速度越來越快，由於這些資源消耗與廢棄物處理的問題，循環經濟的想法被提出來，從生活中的種種廢棄物中尋找可再利用的東西成為了現今人們的目標。在全世界裡，農業廢棄物一直是佔所有廢棄物裡的一大部分，包含了稻殼、甘蔗渣、大麻莖等等，如何將這些含碳的農業廢棄物加以處理使其產生經濟價值，將這些碳材循環高值化成為了重要議題，目前據大家所知，碳材料在能源儲存方面，最具應用價值的就是石墨，然而傳統生產人工石墨所需的轉換溫度大約在3000度左右，這需要消耗大量的能源及時間，最近有研究團隊提出運用熔融鹽低溫電化學法能實現電化學石墨化，並且也成功將其石墨產物進行了電池效能的分析。此篇研究中先是將與德國農業部合作的大麻莖廢棄物，運用水熱法的方式將其纖維素轉變為方便石墨化的生物碳黑，在成功將其石墨化，並且想將此技術加以應用在解決氧化矽負極材料在鋰離子電池裡的膨脹問題上，於是我們將氧化矽粉末混合大麻莖碳黑進行熔融鹽電化學反應，成功在氧化矽上生成一層多孔的碳化物衍生物以保護氧化矽負極在鋰離子電池裡膨脹的問題。接著，運用氯化銅在高溫狀態下容易與碳化矽產生反應，進而去控制碳化物衍生物層的孔洞大小，使其在保護氧化矽負極的同時不犧牲太多的電容量。此研究不僅將低溫熔融鹽電化學法運用在更多的生物廢棄物上，且成功實現在氧化矽負極上生成一層碳材的保護層，去解決現在氧化矽負極在鋰離子電池上最大的膨脹問題。在本研究中，將擁有一層碳化物衍生物保護層的氧化矽材料進行電化學測試，該樣品在鋰離子電池的測試中，放電的電容量可以達到450 mAh/g，且在300圈的充放電測試後，仍然保有超過90%的庫倫效率。

In recent decades, with more and more population, more and more wastes are made, so the idea of circular economy is coming out. The idea of circular economy has been proposed to recycle various kinds of waste and to increase their values, including agriculture wastes. There is a lot of carbon contained in agriculture wastes, so try to transform the carbon inside agriculture wastes to graphite which is highly valuable becomes some researcher’s goals. Recently, electrochemical graphitization has been investigated in molten CaCl2. However, previous studies only transformed amorphous carbon to graphite and increased the graphitization degree. In this work, silicon anode has high potential, but only needs to overcome the problem of expansion, so coating some strong structure to protect silicon and the lithium battery becomes one of the solutions. Through this molten salt route, but change the salt to ternary salt (MgCl2/NaCl/KCl), and add some CuCl2 into silicon-carbon composite which is replacing the amorphous carbon ingot. The result is shown that the carbide derived carbon thin film is formed on silicon and carbon boundary. The carbide derived carbon thin film can protect the expansion from silicon when it acts as anode in lithium battery, but if the thickness too thick or the total pore volume of carbide derived carbon too small, it will make the lithium ions cannot react with silicon, so the result is shown that adding CuCl2 can control the total pore volume of carbide derived carbon. This can make the silicon anode have better battery performance in lithium ion battery. The obtained SiO2@CDC composite delivers a specific discharge capacity of 450 mAh/g at 0.1 A/g, even after 300 cycles with over 90% cycle efficiency.

Abstract i
摘要 ii
致謝 iii
Table of Contents iv
List of Figures caption vi
List of Table caption viii
Chapter 1 Introduction 1
1.1 Introduction of Bio-carbon recycling 1
1.1.1 The advantage of circular economy 1
1.1.2 Potential application of hemp after hydrothermal process 2
1.2 Introduction of Graphite 2
1.2.1 Application of Graphite 3
1.2.2 Graphitization process 3
1.2.2.1 High-temperature treatment of graphitization 4
1.2.2.2 Molten-Salt electrolysis 5
1.3 Introduction of CDC 8
1.3.1 The characteristics of CDC 8
1.3.2 Application of CDC 9
1.4 Lithium ions battery 10
1.4.1 Lithium ions battery overview 10
1.4.2 Working mechanism of lithium ions battery 11
1.4.3 Silicon as the anode of lithium ions battery 12


Chapter 2 Motivation 15
2.1 The superiority of Si-based anode materials 15
2.2 Thickness of CDC layer in Si anode 15
Chapter 3 Material Synthesis and Characterization 16
3.1 Preparation of Hemp Carbon Ingot 16
3.2 Synthesis of Graphitic Carbon in Molten Salt 17
3.3 Preparation of Carbon/Silicon composite Ingot 18
3.4 Synthesis of CDC film in Molten Salt 18
3.5 Control CDC film by adding CuCl/CuCl2 into precursor 19
3.6 Lithium IonS Battery Fabrication and Measurement 20
3.7 Material Characterization 20
Chapter 4 Result and discussion 22
4.1 Transfer hemp fiber into carbon black by hydrothermal process 22
4.2 Graphitization of hemp carbon black by molten salt process 23
4.3 Use carbon-silicon composite to form CDC by molten salt process 27
4.3.1 Material analysis 27
4.3.2 Characteristic of CDC film & mechanism discussion 31
4.3.3 Battery and electrochemical performance in LIBs 33
4.4 Control CDC film by adding CuCl2 into precursor 38
4.4.1 Material analysis 38
4.4.2 Mechanism discussion of adding CuCl2 to control CDC film 44
4.4.3 Battery and electrochemical performance in LIBs 46
Chapter 5 Conclusion and Future works 51
Chapter 6 Reference 52

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