隨著各種再生能源的發展，開發鋰離子二次電池作為未來的電力的儲能系統與裝置也日益備受重視，例如應付風能與太陽能等間歇性再生能源輸出之定置型儲電系統以及裝載於電動車的動力鋰電池裝置。鈦酸鋰負極材料由於穩定的結構與安全工作電壓範圍，使其在鋰電池安全性與長循環壽命方面具有相當的優勢。然而鈦酸鋰是絕緣性材料，因此本研究致力於藉由結構缺陷與碳的批覆來提升導電度以改善其快速充放電性能。
論文第一部分探究還原性氣氛對於鈦酸鋰的影響，研究結果發現具有氧空缺之鈦酸鋰除了在導電性上的提升，鋰離子擴散速率也因為鈦酸鋰原子結構的些微改變而獲得改善。有鑑於在追求快速充放電性能時，導電度和鋰離子擴散能力須同時促進，因此論文第二部分提出一個結合高分子與還原性氣氛的改良式固態合成法，其合成的鈦酸鋰同時擁有多孔性結構、碳的導電網絡以及利於鋰離子擴散的結構，在5 C快速充放電之下能提供155 mAh/g的電容量(89%的鈦酸鋰理論電容, 175 mAh/g)且具有結構穩定性，在200圈循環測試仍能維持初始的電容量。

In the society that several alternative energy sources are developing, lithium ion batteries have being designed to meet the raising requirement of electric vehicle (EV) and back-up storage systems. Li4Ti5O12 is a promising anode material for both high-power and high-safety lithium-ion batteries (LIBs). Li4Ti5O12 possesses the advantages of high safety and long cycle life, due to robust spinel structure and no solid electrolyte interface (SEI) formation. However, Li4Ti5O12 is electron insulated. Hence, this study aims to improve the electron conductivity through atmosphere control and carbon-assistance to promote its high-rate performance.
Initially, the study probes into the effect of reductive atmosphere. Beyond the enhancement of electron conductivity, it is found that the lithium diffusion is also facilitated due to disorder structure. Furthermore, in view of that both lithium diffusivity and electron conductivity should be promoted for high rate capability, polymer-assisted solid-state method incorporated with reductive atmosphere is proposed. Porous structure, carbon network and disorder structure are synthesized under one-step synthesis, resulting in the outstanding electrochemical performance. The high-rate capacity of 5C reaches 155 mAh/g, 89% of theoretical value, and retained the initial value after 200 discharging/charging cycles.

List of Tables III
Figure Captions IV
Abstract VIII
Chapter 1 Introduction 1
1.1 Background 1
1.2 The evolution of anode materials 2
1.3 Motivations and objectives in this study 4
Chapter 2 Literature Review 11
2.1 Introduction to lithium ion batteries 11
2.1.1 The evolution of lithium ion batteries 11
2.1.2 The reaction mechanism of lithium ion batteries 12
2.1.3 Anode material 14
2.2 Spinel Li4Ti5O12 anode materials 16
2.2.1 Basic concepts of Li4Ti5O12 16
2.2.2 Control of morphology 18
2.2.3 Control of intrinsic structure 21
2.2.4 Conductive surface coating 25
Chapter 3 Experimental Details 45
3.1 Synthesis procedure 45
3.1.1 Mesoporous Li4Ti5O12 via one-step synthesis 45
3.1.2 Mesoporous Li4Ti5O12-x with atmosphere controlled 45
3.1.3 Carbon-assisted porous Li4Ti5O12-x via one-step synthesis with atmosphere control 45
3.2 Characterization and analysis 46
3.2.1 Phase identification 46
3.2.2 Composition evaluation 46
3.2.3 Morphology observation 46
3.2.4 Thermal analysis 47
3.2.5 Surface area measurement 47
3.2.6 Bond structure investigation 47
3.2.7 Electrochemical characterization 48
Chapter 4 Results and Discussion 49
4.1 Effect of reductive atmosphere on lithium titanate 49
4.1.1 Phase identification 50
4.1.2 Morphology observation 52
4.1.3 Optical properties of lithium titanate 52
4.1.4 Electrochemical analysis 55
4.2 Carbon-assisted porous Li4Ti5O12-x via one-step synthesis with atmosphere control for high-rate capability and cycling retention 70
4.2.1 One-step synthesis with atmosphere control 70
4.2.2 Identification of phase and composition 72
4.2.3 Morphology observation 72
4.2.4 Optical properties of carbon and lithium titanate 75
4.2.5 Electrochemical analysis 77
4.3 The architecture design of lithium titanate for high-rate performance 81
Chapter 5 Conclusions 105
References 107
Appendix 113

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