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  • 學位論文

PEO/LiClO4/mesoporous silica複合高分子電解質之製備及性質研究

Preparation and characterization of PEO/LiClO4/mesoporous silica composite polymer electrolytes

指導教授 : 陳玉惠
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摘要


本研究主要利用高分子量之Poly(ethylene oxide)(PEO)、適當濃度之LiClO4與低添加量之自製中孔洞二氧化矽,製備出一完全非結晶性之PEO/LiClO4/mesoporous silica複合高分子電解質系統。利用差式掃描卡計(DSC)、X光繞射分析儀(XRD)、傅立葉紅外線光譜儀(FT-IR)、固態核磁共振儀(7Li solid-state NMR)、交流阻抗分析儀(AC-Impedence Analyzer)、掃描電子顯微鏡(SEM)、能量散射光譜儀(EDS)及電化學分析儀(Electrochemical System)探討其熱性質、結晶性、各成份間作用力、離子解離情形、鋰離子的環境、離子導電度、活化能、表面形態、分散情形與鋰離子傳導係數。 結果顯示,當EO/Li=6時,O6高分子電解質為一非結晶性之高分子電解質,其室溫導電度可達2.37×10-5S/cm。當2wt.%之中孔洞二氧化矽加入後,可均勻的分散在O6高分子電解質系統中,所製備之複合高分子電解質(O6A2)並沒有明顯的相分離與自聚(aggregation)現象,其室溫離子導電度高達7.09×10-5S/cm,接近實用值的範圍(10-4S/cm),且鋰離子傳導係數(t+)值亦高達0.67,此結果均比目前所報導之PEO/LiClO4/SiO2電解質系統來得高。可歸因於(1)在路易士酸鹼作用力下,中孔洞二氧化矽上的氧原子會與鋰離子產生作用力,與高分子產生競爭效應,減弱鋰離子與高分子間的作用力,增加高分子的鏈節運動,並在中孔洞二氧化矽表面形成新的傳導途徑;(2)中孔洞二氧化矽表面之氫氧基亦會與高分子及陰離子產生作用,抑制高分子的再結晶與離子的再結合,增加鋰離子的移動性。

並列摘要


In this study, a series of totally amorphous PEO/LiClO4/mesoporous silica nanocomposite polymer electrolytes were prepared with high molecule weight polyethylene oxide, high concentration lithium perchlorate and low content of a homemade mesoporous silica. The SEM/EDS images of the nanocomposite polymer electrolytes indicated that 2wt.% of the mesoporous silica was well dispersed in the PEO polymer electrolyte matrix. The interactions in the system and possible conduction mechanism were studied by DSC, XRD, FT-IR, and 7Li-NMR analysis. It was found that conductivity was significantly improved by the addition of the as-prepared mesoporous silica. A maximum ambient conductivity value of 7.09×10-5 S/cm was obtained for the nanocomposite polymer electrolyte O6A2. The AC-DC polarization results showed that the lithium ion transference number(t+) of O6A2 was about 0.67, which is the highest value reported in PEO/LiClO4/SiO2 system up to now. The high ionic conductivity and lithium ion transference number suggested that it can be used as a potential candidate of the electrolyte material for lithium polymer batteries.

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