在過去幾十年當中，鋰離子電池除了是許多研究團隊的研究對象，更已廣泛地被使用在許多可攜式裝置或電動車當中。然而，目前商用化鋰電池中含有由鋰鹽以及有機溶劑組成的電解液，這些液體有可能因包裝不良造成洩漏，且分解出會對人體造成危害的產物，另外，這些可燃性的有機溶劑有可能引起燃燒或爆炸，以上這些問題皆讓鋰電池的使用存在著安全上的疑慮，因此許多研究團隊致力於發展固態電解質，其中複合型固態電解質結合了無機材料和有機分子的優勢，使其成為具有發展潛力的固態電解質材料。
本實驗的第一部分以溶膠凝膠法製備NASICON型固態電解質LATP粉體，粉體的結晶結構、形貌分別以X光繞射儀及場發射型掃描式電子顯微鏡進行量測與研究。進一步燒結成緻密的陶瓷碇後，測得在30 ℃和60 ℃下的鋰離子傳導率分別是2.378 × 10-4及7.596 × 10-4 S/cm。
第二部分的實驗則是將不同比例的LATP粉體（0、10、50 wt%）加入聚乙二醇（PEO）及過氯酸鋰（LiClO4）中形成複合型固態電解質，在加入LATP後能大幅的將整體的電化學穩定窗口提升至5 V。對以鋰金屬作為對稱電極組成的對稱電池進行電流循環測試，發現以添加50 wt% LATP的複合型固態電解質組成的對稱電池的整體阻抗值為最小值。
實驗的第三部分將複合型固態電解質與磷酸鋰鐵（LiFePO4）、鋰片、10 μL EC/DMC組成半固態電池，並對其進行多樣的電化學測試。其中以添加50 wt% LATP的複合型固態電解質組成的電池在變速率充放電測試中有最優的表現。

Over the past decades, the safety hazard results from the use of flammable liquid electrolytes and the demand for higher energy density batteries have motivated the research in the area of solid-state electrolytes. Among a variety of solid-state electrolytes, composite solid electrolytes (CSEs) have attracted great attention and been viewed as a promising candidate for the next-generation energy storage system.
In the first part of this work, the NASICON-type ionic conductor, Li1.3Al0.3Ti1.7(PO4)3 (LATP), was synthesized by sol-gel process. It’ s structure and morphology were further examined by X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopy measurement. In addition, the ionic conductivity of LATP at 30 ℃ and 60 ℃ were 2.378 × 10-4 and 7.596 × 10-4 S/cm, respectively.
In the second part, the CSEs composed of PEO, LiClO4, and LATP particles were prepared via slurry casting method. The electrochemical stability window can be enlarged to 5 V by the incorporation of LATP. In the measurements of the compatibility with lithium metal of the CSEs, it was found that the addition of LATP could lead to electrochemical instability.
In the final part, the LiFePO4/CSE/Li hybrid solid-state cells were assembled and investigated. The results show that the incorporation of 50 wt% of LATP would greatly improve the rate capability.

Chapter 1 Introduction 1
Chapter 2 Literature Review 5
2.1 Inorganic solid electrolyte 5
2.1.1 Introduction of inorganic solid electrolyte 5
2.1.2 NASICON-type 7
2.2 Poly(ethylene oxide) 9
2.2.1 Mechanism of ionic transport in PEO 10
2.2.2 Limitations of PEO 10
2.3 Strategies of improving properties of PEO 11
2.3.1 Polymer blend 12
2.3.2 Plasticizer 13
2.3.3 Composite solid electrolyte: Inert filler 14
2.3.4 Composite solid electrolyte: Active filler 16
Chapter 3 Experimental Procedure 21
3.1 Materials preparation 21
3.1.1 Synthesis procedure 21
3.1.2 Sintering procedure 23
3.1.3 Preparation of composite solid electrolyte 23
3.1.4 Preparation of LiFePO4 cathode 24
3.1.5 Hybrid solid-state LiFePO4/CSE/Li cell assembly 25
3.2 Material characterization 26
3.2.1 X-ray Diffraction (XRD) 26
3.2.2 Scanning electron microscope (SEM) 27
3.2.3 Raman spectroscopy 27
3.2.4 Particle size analyzer 28
3.3 Electrochemical characterization 28
3.3.1 Cycle performance and rate capability test 28
3.3.2 Electrochemical impedance spectroscopy (EIS) 28
3.3.3 Linear sweep voltammetry (LSV) 29
Chapter 4 Results and Discussion 30
4.1 LATP 30
4.1.1 The synthesis of LATP powder 30
4.1.2 Lithium ionic conductivity of LATP 32
4.2 Composite solid electrolyte (CSE) 36
4.2.1 Material characterizations of CSEs 36
4.2.2 Electrochemical stability windows of CSEs 38
4.2.3 Compatibility 39
4.3 Performance of LiFePO4/CSE/Li cells 44
4.3.1 Rate capability 44
4.3.2 Cycle performance 50
Chapter 5 Conclusion 52
Chapter 6 Future prospects 53
Referees 54

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