本研究主要係利用三種不同分子量之聚醚交聯劑，分別混摻高分子前驅物與商用電解液之三種系統於鋰金屬電池中引發原位自由基聚合，以應用於膠態高分子電解質之研究，並分別按照基材分子量: 600、900、2000，命名為GPT600、GPT900、GPT2000。利用拉曼光譜儀及固態核磁共振儀確認各系統與鋰離子作用之聚醚基對鋰鹽解離能力之影響，與藉由改變基材的鏈長度，如何改變鋰離子的移動性;在熱差微分掃描分析儀中探討高分子基材的熱穩定性。離子傳導度在各組成的範圍介於 6.0×10-3 to 1.2×10-2 S cm-1，在50 ℃時可接近液態電解質的1.0×10-2 S cm-1。此外，隨聚醚鏈長的增加穩定電位窗可達一般液態電解質的5.0 V。於鋰電池循環壽命測試中發現，在4 C快速充放電速率下，三種系統的庫倫效率皆維持於99 %以上，GPT600系統在第100圈時並未顯著電容衰退而一般電解液的電容衰退率在第100圈後則非常大。經由SEM影像觀察充放電後鋰金屬表面與截面，相較一般液態電解質的SEI層厚並且較多裂縫，使用本研究之膠態電解質則於鋰金屬表面較無上述問題產生，並且發現系統的基材鏈長度越短，其在鋰金屬上的SEI層相對平坦且薄。由以上所述可歸納本研究所製備膠態高分子電解質可以應用於鋰電池中，並且得到聚醚高分子的鏈長度與鋰電池系統間的關係。

The gel polymer electrolytes were prepared by different length of crosslinkers, polymer precursors, and commercial liquid electrolytes via in-situ free radical polymerization in lithium metal batteries. In this study, the gel polymer electrolytes contain various crosslinkers of 600, 900, and 2000 molecular weight, which are named GPT600、GPT900、GPT2000, respectively. Raman spectrameter and 7Li magic-angle spinning NMR elucidate the interactions between lithium ions and poly( ethylene oxide ) for various systems, which indicates degree of crosslinking affects the mobility of matrix polymer backbones. Differential scanning calorimetry was used to study the behavior of thermal stability of gel polymer electrolytes. Gel polymer electrolytes not only provide mechanical strength but also have good ionic conductivity. The ionic conductivity of gel polymer electrolytes for each system ranges from 6.0×10-3 to 1.2×10-2 S cm-1 and also achieves nearly 1.0×10-2 S cm-1 at 50 ℃, which is closed to that of the liquid electrolyte. Further, electrochemical windows were obtained by LSV method presenting the LSV curves of gel polymers are roughly 5.0 V, which is notably closed to that of the liquid electrolyte. On the other hand, cycling performance at 4 C demonstrates a reversible cycling process for three systems and keeps the coulombic efficiency above 99 %. GPT600 exhibited a remarkable improved cycling performance after 100 cycles compared to that of the cell with the liquid electrolyte after 100 cycles. We observed the surface of the Li anode obtained from the cells after 100 cycles at 4 C. In a contrast, gel polymer electrolytes feature a compact and smooth SEI layer but the liquid electrolyte forms an inhomogeneous layer with crack. Especially, GPT600 and GPT900, higher degree of crosslinking, indicate a stable and thin layer with low resistance upon cycling.
All the above-mentioned properties indicate that the cross-linked polymer electrolytes can be a promising candidate for lithium metal batteries.

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