複合高分子電解質

林紀昌(Chi-Chang Lin)

指導教授 ： 諸柏仁

國立中央大學/理學院/化學系/碩士(2006年)

摘要

有機-無機奈米複合材料為高分子電解質帶來許多電性與熱性質上的改善，除了優越的機械穩定性、高離子導電度、大的電化學穩定區間之外，尚能提供與電極良好的介面穩定性。
針對本研究所製備之二氧化鈦奈米管以及經過高分子表面修飾的二氧化鈦奈米管，使用XRD、NMR、XPS、TEM、TGA等儀器進行鑑定。將修飾後的二氧化鈦奈米管進一步製備成複合高分子電解質，由SEM表面型態觀察到相容性的提升，由離子導電度的分析也證實經修飾後，相較於僅只是摻合的方式，能有效提升導電度超過一個級數（order）。XPS及FT-IR的分析則指出鋰鹽在電解質系統中能有效的解離，減少離子對的情形。
藉由AC-Impedance與DSC的研究，顯示在不同製備條件的複合高分子電解質中，不僅二氧化鈦奈米管能有效藉由短暫交聯結構的形成，使高分子重組作用降低、增加非結晶區塊，並延緩剩餘高分子結晶區塊的結晶速率；同時也發現發現，小分子量高分子的採用能有效提高離子導電度；適當的成膜溶劑選擇，除了能提供高介電常數促使鹽類解離外，還能利用奈米管的特殊表面微結構或是管徑中空的位置做溶劑儲存（retain）的功用，即使在高溫（90°C）也不會逸失；不同鋰鹽的使用，也能從導電度行為上觀察到二氧化鈦、高分子與鋰鹽之間的作用是否於一開始就已達平衡狀態，亦或需要做一高溫的熱催化，來促使三者間的作用或配對情形達平衡狀態；使用不同合成製備方式的二氧化鈦奈米管，也能觀察到由於其表面結構缺陷濃度的不同，而影響導電度及高分子熱性質的行為。最後，發現在複合交聯型高分子電解質的系統中，酚醛樹酯與高分子所形成相互貫穿的網狀區塊，能有效限制高分子的結晶行為，交聯劑的添加則大幅提昇的薄膜的機械穩定性，而二氧化鈦奈米管的使用，則避免了結構交聯過度所帶來導電度的大幅衰退。

關鍵字

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並列摘要

Organic-inorganic nano-composite bring lots of improvements in electric and thermal properties, such as excellent mechanical stability, higher ionic conductivity and wide electrochemical stability, and also provide better interface stability with electrode.
This research focus on the preparation of TiO2 nano-tube and surface modification of TiO2 nano-tube with polymer which can be characterized by using XRD, NMR, XPS, TEM and TGA etc. Composite polymer electrolyte made by surface modified TiO2 nano-tube exhibit better compatibility from SEM surface morphology observation and an increase in ionic conductivity more than one order than that of blending ones. XPS and FT-IR also indicated polymer electrolyte containing TiO2 nano-tube can efficaciously dissociate the lithium salt and decrease the ion-pairing occurring.
Composite polymer electrolyte made with a number of variable components were systematically study to find their impact upon the electrochemical properties of the resulting materials. TiO2 nano-tube surface group can act as a cross-linking center for the polymer segments, which reduced the polymer reorganization, increased amorphous domain and delay the rate of recrystallization. It’s generally observed the lower molecular weight samples yielded the higher ionic conductivity. A proper choice of solvent will not only increase the order of salt dissociation but also can be stored in TiO2 tubular microstructure. Conductivity behavior suggested specific salt will re-distribute between TiO2 nano-tube and polymer chain to reach equilibrium state. TiO2 nano-tube with different `concentration of surface defect will be a critical factor affect the conductivity and thermal proper of polymer electrolyte.
In the composite/cross-linking polymer electrolyte, the interpenetrating network structure between phenolic and polymer chain can be efficiently hindered polymer crystallization, the cross-linker promoted mechanical stability, and the using of TiO2 nano-tube avoid the dramatically fadedness of conductivity came from over cross-linking.

並列關鍵字

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參考文獻

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