在过去的20年中，鋰離子電池（LIB）在市場上發揮了重要作用，作為其他可再充電電池系統具有更高重量和體積容量的主要電源供應商。 然而，目前的鋰離子電池技術不能滿足從便攜式電子設備到全電動車輛和智能電網的廣泛應用的能源和電力需求。 在這方面，亞洲碳素股份有限公司和Tuan教授的實驗室已經合作致力於漸進的LIB。目的是找出基於高容量，高庫侖效率，循環穩定的LIBs組裝改性石墨的最佳條件。這些改性樣品最初是石墨材料，其已經在高壓下處理以轉化其形態。樣品處理過程由公司進行。 樣品數量為32個樣品，分別為G201，G202，G203至G232。為了達到這個目的，這些改性石墨樣品最初在相同的工藝（最近在第2章中描述）的半電池中組裝了陽極電極，以便在高容量，良好的庫侖效率和循環穩定性方面找到好的樣品。所有生產的漿料包括83,50重量％的活性物質，8.0重量％的超級P和8.5重量％的PVDF在NMP溶液中攪拌1.5小時。然後，他們的自行車錶演仔細對比，導致獲得四個最佳樣本。在不同的條件下進一步研究這些樣品，例如（i）各種塗層厚度和（ii）不同種類的電解質，以找出最佳樣品，並獲得組裝基於鋰離子電池的改性石墨的配方。 此外，通過SEM圖像分析樣品，IV檢驗以獲得對其特徵的更多了解。
為了超越基於負極的改性石墨低能力的弱點，作者不斷開展了“矽/石墨複合材料作為陽極材料”的工作，以克服這個問題。 研究表明，矽/石墨複合材料在比容量和初始效率方面有顯著改善。 與僅石墨粉末相比，電極具有更高數量的充電/放電循環，具有更穩定的放電容量。

In the last two decades, Li-ion batteries (LIBs) has played a critically important role in the market as a primary power supplier with a higher gravimetric and volumetric capacity than other rechargeable-battery systems. However, current LIB technologies cannot satisfy the energy and power requirements of a wide range of applications, from portable electronic devices to all-electric vehicles and smart grids. In this regard, Asia Carbons and Technology INC company which locates at Taoyuan country, Taiwan (R.O.C) and Prof. Hsing-Yu Tuan Labortary have cooperated to dedicate to the progressive LIBs. Hence, the study was a cooperative work between Prof. Hsing-Yu Tuan Lab and the company. The aim was to find out the optimal conditions for assembling modified-graphite based on LIBs with high capacity, high coulombic efficiency, cycling stable. These modified samples were originally graphite materials, which has been treated under the high pressure to transform their morphologies. The sample treatment process was carried out by the company. The number of samples were 32 samples, namely G201, G202, G203 to G232 in order. In order to achieve the purpose, those modified graphite samples were initially assembled anode electrode in half-cells under the same process (described lately in chapter 2) to find out the good samples in terms of high capacity, good coulombic efficiency and cycling stable. All the produced slurries included 83,50 wt% active materials, 8.0 wt% super P and 8.5 wt% PVDF stirred in NMP solution for 1.5 hours. Then, their cycling performances were carefully compared to each other, based on the predefined goals (KPI), which resulted in obtaining four best samples. These samples were investigated further under different conditions such as (i) various coating thickness and (ii) different kinds of electrolytes to find out the best sample as well as to gain the recipe for assembling modified-graphite based on lithium-ion batteries. Besides that, those samples were analyzed via SEM images, IV test to obtain more understanding about their characteristics.
It is found that the modified sample named G227 stood out as a potential candidate for anode electrode in lithium battery, since it performed stably over 50 cycles with high capacity above 320 mA h/g. Another finding was that electrolyte system which includes ethylene carbonate (EC): dimethyl carbonate (DMC): fluoroethylene carbonate (FEC) 4.5:4.5:1 (v:v) in LPF6 has enhanced the good cycling performance rather than fluoroethylene carbonate (FEC): diethyl carbonate (DEC) 3:7 (v.v) and ethylene carbonate (EC): dimethyl carbonate (DMC) 1:1 (v/v) in LPF6 system. However, this work currently facing an issue that the average capacity is quite low, which needs a lot effort to solve.
In order to surpass the weakness of low capacity of modified graphite based on negative electrodes, the author continuously carried out the work named “silicon/graphite composites as anode materials” to overcome the problem. The study indicated that silicon/graphite composite has a significant improvement on specific capacity and the initial efficiency. The electrodes sustain a higher number of charge/discharge cycles with a more stable discharge capacity compared to the graphite powders only. Two full-cell coins show outstanding stability for the first 50 cycles, leading to a capacity retention of 1st sample and 2nd one are 94.68% and 92.56%, respectively. The average initial efficiency is over 86.00%. This result has exceeded the standard KPI (>85%). Besides that, the cycle performance of Si/graphite composites based-on pouch cell is also investigated. Its areal capacity and specific capacity are 3.92 mA h/cm2 and 604 mA h/g, respectively, which is much better than expected.

文章摘要 i
Abstract ii
Content iv
List of Figures vi
List of Tables ix
Chapter 1. Modified graphite as highly-conductive anode materials for conductive carbon free lithium batteries 1
1.1. Introduction 1
1.1.1. Electrochemical principles of the lithium-ion cell 2
1.1.1.1. Graphite electrode 2
1.1.1.2. Lithium ion intercalation into graphite 2
1.1.1.3. Solid electrolyte interface (SEI) 3
1.1.1.4. Electrolytess 4
1.1.2. Modified graphite 5
1.1.3. Motivation for the study 6
1.2. Materials and Methodology 7
1.2.1. Materials 8
1.2.2. Methodology 8
1.2.2.1. Testing for cycle capacity of the modified graphite samples 8
1.2.2.2. Characterization 9
1.2.2.3. Testing for capacity at various conditions 10
1.2.3. Fabrication of LIBs 10
1.3. Results and Discussion 13
1.3.1. Comparison the capacity of modified samples 13
1.3.2. Characterization 15
1.3.3. Capacity performance of three samples at different conditions 17
1.3.3.1. G220 cycling performance at different conditions 17
1.3.3.2. G223 cycling performance at different conditions 17
1.3.3.3. G227 cycling performance at different conditions 18
1.3.3.4. G231 cycling performance at different conditions 18
1.3.3.5. Capacity performance over 50 cycles 19
1.4. Conclusion and Future Work 20
1.5. References 22
Chapter 2. Silicon-graphite composites as negative electrode for lithium ion batteries 23
2.1. Introduction 23
2.2. Materials and Methodology 27
2.2.1. Materials 27
2.2.2. Methodology 28
2.2.3. Fabrication of full-cell coin 29
2.2.4. Fabrication of pouch cell 30
2.2.5. Lithium-ion battery electrochemical characterization 31
2.3. Characterization 31
2.4. Result and Discussion 32
2.4.1. SEM and EDS 32
2.4.2. Lithium-ion battery electrochemical characterization 32
2.5. Conclusion 34
2.6. References 35

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