傳統鋰離子電池存在電池漏液、爆炸等風險，在行動裝置、電動交通工具普及的時代，一個安全且高能量密度的電池為大家所追求的目標。本論文研究共熔鹽與高分子形成之膠態電解質及其鋰電池應用，以高分子PVdF導入鋰鹽LiTFSI與N-Metylacetamide形成的共熔鹽溶劑製備成膠態電解質膜。藉由導離子度測試、線性掃描伏安法、循環伏安法來了解膠態電解質的電化學特性及穩定性，其導離子度在室溫可達6×10-4 S cm-1，電化學窗口在4.6 V (V vs. Li+/Li)。以磷酸鋰鐵(LFP)半電池在室溫充放電測試測試，充放電速率0.5C下可以達到電容量150 mAh g-1，0.1C能循環100圈以上，相較於同系統的液態共熔鹽電解質及共熔鹽膠態電解質，PVdF共熔鹽膠態電解質的電容量表現更高，但由於不穩定的SEI (Solid Electrolyte Interface)使半電池在更高速率充放電條件出現快速衰退的現象，在添加FEC (Fluoroethylene Carbonate)後，室溫充放電在1C有超過140 mAh g-1的電容量表現，0.2C循環壽命也能重複100圈以上，利用電化學阻抗分析、鋰枝晶測試及SEM證明添加FEC使負極鋰金屬上的SEI獲得改善。拉曼分析協助我們了解電解質中鋰離子的解離情況，加上DSC分析，我們提出PVdF膨潤的海綿狀膠態電解質模型，膠態電解質的熱穩定性佳，極限氧指數(Limiting Oxygen Index, LOI)為23，屬於耐燃材料，安全性較傳統液態電解質來的高。

We introduce PVdF-DES gel type electrolyte called “eutectogel”. The DES is base on lithium bis(trifluoromethane sulfone)imide (LiTFSI) and N-methylacetamide(MAc). Both of the DES and PVdF polymer are flame resistant, and make the gel electrolyte has good safe property. The optimized ratio of PVdF eutectogel achieve ionic conductivity exceeding 6×10-4 S cm-1 at room temperature. The electrochemical window of anodic stability is 4.6 V (V vs. Li+/Li). In the test of LiFePO4/Li half cell, the 0.5C charge-discharge capacity reach 160 mAh g-1 at room temperature, and the retention of 0.1C long term 120 cycle life test is 96.9%. However, due to the poor stability of Solid electrolyte interface (SEI), the capacity of LFP half cell decay rapidly under high C-rate charge and discharge. After adding FEC, LiFePO4/Li half cell can run 1C charge-discharge, and the capacity reach 140 mAh g-1 at room temperature. In long term cycling, Eutectogel with FEC additive also run over 100 cycles at 0.2C. Characterizing by impedance analysis, dendrite test and SEM of lithium meatal, we prove that SEI is improved by FEC additive. Raman spectrum, SEM and DSC also help us understand the morphology of eutectogel membrane, than the PVdf sponge gel electrolyte model is provided.

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