近年來隨著現代科技的快速發展，人們對於電池的需求也持續增加，因此擁有大比電容量的金屬電池系統備受關注。其中，因鎂擁有高體積比電容量、地殼豐富度高、低成本、環境友善以及不易形成枝晶(dendrite)等優點，可充電鎂電池是作為新一代金屬電池的候選者之一。然而，可充電鎂電池目前尚無法商業化，因為適當的電解質仍是可充電鎂電池系統中的一大挑戰。因此，大部分的學者專注於研究鎂電池電解質的特性以及電池的性能，但關於金屬負極在充放電時的特性並沒有太多深入的探討。因此，本論文將針對可充電鎂電池金屬負極在充電時的電鍍行為及微結構進行研究，並著重在不同參數下鎂鍍層的微結構分析以及電化學行為。
本研究使用all phenyl complex (APC)電解質進行定電流密度的電鍍實驗，分別在鎂電極及可用於無陽極式(anode-free)電池架構的銅集電器(current collector)上，透過改變電流密度及電容量製備出不同參數下的鎂鍍層，並探討在不同參數下的充電曲線以及鎂鍍層的微結構變化。本研究亦進行定電壓的電鍍實驗，並使用Scharifker-Hill模型探討電鍍初期的成核機制。結合電化學量測與鍍層的微結構及結晶取向分析，探討可充電鎂電池負極上鎂鍍層的電鍍機制。
研究結果顯示，鎂鍍層的晶粒尺寸隨著電容量的增加而增大。而隨著電流密度的增加，充電曲線往負電壓移動，鎂鍍層傾向均勻沉積，並在-2.25 mA/cm2的電流密度下完全覆蓋底材，並使鎂鍍層的晶粒尺寸變小，且鍍層的結晶取向從(002)轉變至(100)。使用不同底材也呈現出不同的電鍍成核機制，鎂鍍層在銅底材上的沉積為漸進式成核，而鎂鍍層在鎂底材的沉積則無法使用Scharifker-Hill模型得知其成核機制。然而，在鎂電極上進行鎂鍍層沉積較銅底材困難，且在鎂底材上鎂鍍層的晶粒尺寸受電流密度改變的影響較銅底材不敏感。
縱使可充電鎂電池有不易形成枝晶的特點，但本研究在刻意施加大電流密度下仍發現有枝晶生成。若在大電流密度的電鍍前先以較小電流密度預鍍一層種子層(seed layer)，枝晶生長的情形則明顯有所改善。

In recent years, there has been an increasing demand for batteries with the rapid development of modern technology. As a result, metal batteries with high specific capacity receive lots of attention. Among them, rechargeable magnesium batteries are considered one of the candidates for the next-generation metal batteries because of the high volumetric capacity, high natural abundance, low cost, environmental friendliness, and less dendritic structure formation during charging of magnesium. However, rechargeable magnesium batteries have not yet been commercialized because finding a suitable electrolyte for the system is still a big challenge. Therefore, researchers focused on studying the characteristics of the electrolytes and the performance of the batteries. However, research on the characteristics of the metal negative electrodes during charge and discharge is still few. Therefore, this study investigates the electrodeposition behavior and microstructure of the metal negative electrode during charging for rechargeable magnesium batteries, focusing on the microstructure analysis and electrochemical behavior of electrodeposited magnesium under different parameters.
An all phenyl complex (APC) electrolyte was used for the electrodeposition of magnesium under constant current density on a magnesium electrode and a copper current collector for the anode-free applications. Electrodeposited magnesium was prepared under different current densities and charging capacities, and the charging curves and microstructure evolution of the electrodeposited magnesium were investigated. This study also conducted electrodeposition under constant voltage and used the Scharifker-Hill model to analyze the nucleation mechanism at the initial plating stage. A combination of electrochemical measurements, microstructure characterizations, and crystal orientation analysis of the electrodeposited magnesium is used to investigate the electrodeposition mechanism on metal negative electrodes of rechargeable magnesium batteries.
The results show that the grain size of the electrodeposited magnesium increases with the increase in charging capacity. As the current density increases, the charging curve shifts towards more negative voltage, the electrodeposited magnesium tends to deposit more uniformly, and complete coverage of the substrate can be achieved at a current density of -2.25 mA/cm2. Furthermore, with the increase in current density, the grain size of the electrodeposited magnesium decreases, and the crystal orientation of the magnesium changes from (002) to (100). Additionally, electrodeposition on different metal substrates also exhibits different electrodeposition mechanisms. Magnesium deposition on copper substrates follows progressive nucleation, while the deposition of magnesium on magnesium substrates cannot be described by the Scharifker-Hill model to determine the nucleation mechanism. However, magnesium deposition on magnesium electrodes is more difficult than on copper substrates, and the grain size of electrodeposited magnesium on magnesium substrates is less sensitive to the change in current density than on copper substrates.
Even though rechargeable magnesium batteries have the characteristic of less dendritic formation during charging, dendrites are still observed when a high current density was applied. However, the dendrite growth is significantly improved when a seed layer was deposited at a lower current density before electrodeposition at a high current density.

摘要 i
Abstract iii
致謝 v
目錄 vii
表目錄 ix
圖目錄 x
第一章 緒論 1
第二章 文獻回顧 3
2.1 可充電鎂電池 3
2.1.1 可充電鎂電池簡介 3
2.1.2 可充電鎂電池所面臨的困境 7
2.1.3 可充電鎂電池常見的電解質 8
2.1.4 APC電解質 12
2.2 負極鎂鍍層 14
第三章 實驗方法與步驟 17
3.1 實驗流程 17
3.2 實驗材料製備與實驗槽體 18
3.2.1 金屬電極製備 18
3.2.2 電化學實驗槽體與架構 19
3.3 電解質配製 20
3.3.1 無水THF前處理 20
3.3.2 APC電解質配製 20
3.4 電化學量測 22
3.4.1 循環伏安法(CV)量測 22
3.4.2 循環充放電實驗 23
3.4.3 線性伏安法(LSV)量測 23
3.4.4 電化學沉積(電鍍)實驗 24
3.4.5 計時電流法(CA) 25
3.4.6 電化學阻抗分析 27
3.5 電鍍鍍層微結構分析 27
3.5.1 鍍層表面形貌與成分分析 28
3.5.2 鍍層橫截面分析 28
3.5.3 鍍層晶體結構分析 28
第四章 實驗結果 30
4.1 APC電解質性質 30
4.2 工作電極對電鍍鎂鍍層的影響 34
4.3 鎂鍍層微結構與電鍍行為 36
4.3.1 電鍍過程的充電電壓曲線 37
4.3.2 銅電極上的鎂鍍層微結構 38
4.3.3 鎂電極上的鎂鍍層微結構 42
4.3.4 鎂鍍層橫截面分析 45
4.3.5 鎂鍍層成核機制分析 46
4.4 鎂鍍層枝晶的觀測及改善 49
第五章 討論 52
5.1 電化學槽體之Ohmic drop 52
5.2 電解質庫倫效率受銅腐蝕氧化的影響 53
5.3 鎂鍍層電鍍行為與機制 54
第六章 結論 60
第七章 未來展望 62
參考文獻 63

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