本研究採用電紡技術製備高孔隙度纖維膜作為鋰電池膠態電解質系統之隔離膜，並利用表面改質將單離子傳導基修飾於纖維膜表面，藉以提升鋰離子遷移數及幫助鋰金屬表面形成穩定的SEI層。
首先透過FT-IR證實成功將單離子傳導基修飾於纖維膜表面，並在孔隙度、纖維膜表面分析及離子傳導度測試中發現適當修飾單離子傳導基於纖維膜表面可使室溫離子傳導度達9.9ⅹ10-4 S cm-1優於商用隔離膜的2.3ⅹ10-4 S cm-1。此外，尺寸穩定性測試顯示本實驗製備的纖維膜具有相當優異的熱穩定性。至於電化學特性的表現，除了電化學穩定電位窗可達4.45 V且鋰離子遷移數更高達0.625。鋰電池循環充放電測試中，在2C快速充放電條件下，第100圈之電容維持率仍保有85.1 %，而商用隔離膜僅剩下52 %。藉SEM觀察鋰金屬表面，發現經改質的纖維膜可使快速充放電後的鋰金屬表面較薄且平整，最後FT-IR進一步驗證單離子傳導基能在充放電過程中於鋰金屬表面形成保護層，幫助電池的循環壽命。綜觀上述可歸納本實驗經改質之纖維膜不僅擁有良好的電化學特性及優異的熱穩定性，亦能穩定SEI，是鋰電池系統中極具潛力的材料。

The high porosity fiber separators are prepared by electrospinning technique and used in gel polymer electrolytes of lithium battery. In order to improve lithium ion transference number and stabilize the SEI layer, we introduce the single-ion conducting moiety to fibers by surface modification.
First, the single-ion conducting moiety is successfully modified on the surface of the fiber separators and characterized by FT-IR. Incorporating appropriate single-ion conducting moiety on the surface of the fiber separators can make the ionic conductivity up to 9.9ⅹ10-4 S cm-1 at room temperature, which is higher than conventional separator (2.3ⅹ10-4 S cm-1). In addition, the dimensional stability analysis shows that the fiber separators have excellent thermal stability under 200 ℃. As for the performance of the electrochemical characteristics, it exhibits good electrochemical stability (onset potential~4.45 V) and high lithium ion transference number (0.625). The single-ion contained fiber separator demonstrates the capacity retention rate of 85.1 % after 100th cycles at 2 C-rate, while the conventional separator is only 52 %. The surface of lithium anode after 100 cycles at 2 C is observed by SEM. It is found that the surface-modified separators can make the SEI thin and smooth. Finally, FT-IR further verifies that the single-ion conducting moiety can trigger to form the stable passivation layer on the surface of lithium anode during charging-discharging process.

1 Tarascon, J. M. & Armand, M. Issues and challenges facing rechargeable lithium batteries. Nature 414, 359, doi:10.1038/35104644 (2001).
2 Guyomard, D. & Tarascon, J. M. Rocking‐chair or lithium‐ion rechargeable lithium batteries. Advanced Materials 6, 408-412 (1994).
3 Goodenough, J. B. How we made the Li-ion rechargeable battery. Nature Electronics 1, 204-204 (2018).
4 Mauger, A., Julien, C. M., Goodenough, J. B. & Zaghib, K. Tribute to Michel Armand: from Rocking Chair–Li-ion to Solid-State Lithium Batteries. Journal of The Electrochemical Society 167, 070507 (2019).
5 Agarwal, R. R. Activity and Diffusivity of Lithium Intercalated in Graphite. (The author, 1983).
6 Yoshio, M., Brodd, R. J. & Kozawa, A. Lithium-ion batteries. Vol. 1 (Springer, 2009).
7 Electric Vehucle Outlook 2020. Bloomberg.
8 Battery Pack Prices Fall As Market Ramps Up With Market Average At $156/kWh In 2019. BNEF.
9 Wang, Q. et al. Thermal runaway caused fire and explosion of lithium ion battery. Journal of power sources 208, 210-224 (2012).
10 Pender, J. P. et al. Electrode Degradation in Lithium-Ion Batteries. ACS nano 14, 1243-1295 (2020).
11 Li, D., Chen, L., Wang, T. & Fan, L.-Z. 3D fiber-network-reinforced bicontinuous composite solid electrolyte for dendrite-free lithium metal batteries. ACS applied materials & interfaces 10, 7069-7078 (2018).
12 Kerner, M. Ionic LiquidBased Electrolytesfor High-Temperature Lithium-Ion Batteries.
13 Xiang, Y. et al. Advanced separators for lithium‐ion and lithium–sulfur batteries: a review of recent progress. ChemSusChem 9, 3023-3039 (2016).
14 Arora, P. & Zhang, Z. Battery separators. Chemical reviews 104, 4419-4462 (2004).
15 Deimede, V. & Elmasides, C. Separators for lithium‐ion batteries: a review on the production processes and recent developments. Energy technology 3, 453-468 (2015).
16 Li, H. et al. Preparation and properties of poly (ethylene oxide) gel filled polypropylene separators and their corresponding gel polymer electrolytes for Li-ion batteries. Electrochimica acta 56, 2641-2647 (2011).
17 Deng, K. et al. Single-ion conducting gel polymer electrolytes: design, preparation and application. Journal of Materials Chemistry A (2020).
18 Zhang, H. et al. Single lithium-ion conducting solid polymer electrolytes: advances and perspectives. Chemical Society Reviews 46, 797-815 (2017).
19 Li, N. W. et al. A flexible solid electrolyte interphase layer for long‐life lithium metal anodes. Angewandte Chemie International Edition 57, 1505-1509 (2018).
20 Kang, D. et al. In-situ organic SEI layer for dendrite-free lithium metal anode. Energy Storage Materials 27, 69-77 (2020).
21 Gao, J., Shi, S.-Q. & Li, H. Brief overview of electrochemical potential in lithium ion batteries. Chinese Physics B 25, 018210 (2015).
22 Fenton, D. Complexes of alkali metal ions with poly (ethylene oxide). polymer 14, 589 (1973).
23 Berthier, C. et al. Microscopic investigation of ionic conductivity in alkali metal salts-poly (ethylene oxide) adducts. Solid State Ionics 11, 91-95 (1983).
24 Zhou, D., Shanmukaraj, D., Tkacheva, A., Armand, M. & Wang, G. Polymer Electrolytes for Lithium-Based Batteries: Advances and Prospects. Chem 5, 2326-2352, doi:10.1016/j.chempr.2019.05.009 (2019).
25 Ngai, K. S., Ramesh, S., Ramesh, K. & Juan, J. C. A review of polymer electrolytes: fundamental, approaches and applications. Ionics 22, 1259-1279, doi:10.1007/s11581-016-1756-4 (2016).
26 Chen, R., Qu, W., Guo, X., Li, L. & Wu, F. The pursuit of solid-state electrolytes for lithium batteries: from comprehensive insight to emerging horizons. Materials Horizons 3, 487-516 (2016).
27 Wang, M., Braun, H.-G. & Meyer, E. Crystalline structures in ultrathin poly (ethylene oxide)/poly (methyl methacrylate) blend films. Polymer 44, 5015-5021 (2003).
28 Xue, R. & Angell, C. High ionic conductivity in PEO. PPO block polymer+ salt solutions. Solid State Ionics 25, 223-230 (1987).
29 Garcia-Calvo, O., Lago, N., Devaraj, S. & Armand, M. Cross-linked solid polymer electrolyte for all-solid-state rechargeable lithium batteries. Electrochimica Acta 220, 587-594 (2016).
30 Ketkar, P. M., Shen, K.-H., Hall, L. M. & Epps, T. H. Charging toward improved lithium-ion polymer electrolytes: exploiting synergistic experimental and computational approaches to facilitate materials design. Molecular Systems Design & Engineering 4, 223-238 (2019).
31 Weston, J. & Steele, B. Effects of inert fillers on the mechanical and electrochemical properties of lithium salt-poly (ethylene oxide) polymer electrolytes. Solid State Ionics 7, 75-79 (1982).
32 Pitawala, H., Dissanayake, M. & Seneviratne, V. Combined effect of Al2O3 nano-fillers and EC plasticizer on ionic conductivity enhancement in the solid polymer electrolyte (PEO) 9LiTf. Solid State Ionics 178, 885-888 (2007).
33 Liu, Y., Lee, J. & Hong, L. In situ preparation of poly (ethylene oxide)–SiO2 composite polymer electrolytes. Journal of Power Sources 129, 303-311 (2004).
34 Zhao, Y. et al. A new solid polymer electrolyte incorporating Li10GeP2S12 into a polyethylene oxide matrix for all-solid-state lithium batteries. Journal of Power Sources 301, 47-53 (2016).
35 Zhao, C.-Z. et al. An anion-immobilized composite electrolyte for dendrite-free lithium metal anodes. Proceedings of the National Academy of Sciences 114, 11069-11074 (2017).
36 Seino, Y., Ota, T., Takada, K., Hayashi, A. & Tatsumisago, M. A sulphide lithium super ion conductor is superior to liquid ion conductors for use in rechargeable batteries. Energy & Environmental Science 7, 627-631 (2014).
37 Boaretto, N., Meabe, L., Martinez-Ibañez, M., Armand, M. & Zhang, H. Review—Polymer Electrolytes for Rechargeable Batteries: From Nanocomposite to Nanohybrid. Journal of The Electrochemical Society 167, doi:10.1149/1945-7111/ab7221 (2020).
38 Osada, I., de Vries, H., Scrosati, B. & Passerini, S. Ionic‐liquid‐based polymer electrolytes for battery applications. Angewandte Chemie International Edition 55, 500-513 (2016).
39 Zhang, J., Sun, B., Huang, X., Chen, S. & Wang, G. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety. Scientific reports 4, 6007 (2014).
40 Zhu, Y. et al. A composite gel polymer electrolyte with high performance based on poly (vinylidene fluoride) and polyborate for lithium ion batteries. Advanced Energy Materials 4, 1300647 (2014).
41 Dai, K. et al. A borate-rich, cross-linked gel polymer electrolyte with near-single ion conduction for lithium metal batteries. Journal of Materials Chemistry A 7, 18547-18557, doi:10.1039/c9ta05938e (2019).
42 Song, J., Wang, Y. & Wan, C. C. Review of gel-type polymer electrolytes for lithium-ion batteries. Journal of power sources 77, 183-197 (1999).
43 Siyal, S. H. et al. Ultraviolet irradiated PEO/LATP composite gel polymer electrolytes for lithium-metallic batteries (LMBs). Applied Surface Science 494, 1119-1126 (2019).
44 Bohnke, O., Rousselot, C., Gillet, P. & Truche, C. Gel Electrolyte for Solid‐State Electrochromic Cell. Journal of the Electrochemical Society 139, 1862 (1992).
45 Bohnke, O., Frand, G., Rezrazi, M., Rousselot, C. & Truche, C. Fast ion transport in new lithium electrolytes gelled with PMMA. 1. Influence of polymer concentration. Solid State Ionics 66, 97-104 (1993).
46 Guan, X., Chen, F., Li, Z., Zhou, H. & Ma, X. Influence of a rigid polystyrene block on the free volume and ionic conductivity of a gel polymer electrolyte based on poly (methyl methacrylate)‐block‐polystyrene. Journal of Applied Polymer Science 133 (2016).
47 Du Pasquier, A. et al. Differential scanning calorimetry study of the reactivity of carbon anodes in plastic Li‐ion batteries. Journal of the Electrochemical Society 145, 472 (1998).
48 Prasanth, R., Shubha, N., Hng, H. H. & Srinivasan, M. Effect of poly (ethylene oxide) on ionic conductivity and electrochemical properties of poly (vinylidenefluoride) based polymer gel electrolytes prepared by electrospinning for lithium ion batteries. Journal of Power Sources 245, 283-291 (2014).
49 Groce, F. et al. Synthesis and characterization of highly conducting gel electrolytes. Electrochimica Acta 39, 2187-2194 (1994).
50 Zhou, D. Y. et al. Preparation and performances of porous polyacrylonitrile–methyl methacrylate membrane for lithium-ion batteries. Journal of Power Sources 184, 477-480, doi:10.1016/j.jpowsour.2008.05.027 (2008).
51 Long, L., Wang, S., Xiao, M. & Meng, Y. Polymer electrolytes for lithium polymer batteries. Journal of Materials Chemistry A 4, 10038-10069, doi:10.1039/c6ta02621d (2016).
52 Balducci, A. in Ionic Liquids II 1-27 (Springer, 2017).
53 Enabling Technologies: Ionic Liquids. Chem.Files Vol. 5, No. 6.
54 Guan, X. et al. In-situ crosslinked single ion gel polymer electrolyte with superior performances for lithium metal batteries. Chemical Engineering Journal 382, doi:10.1016/j.cej.2019.122935 (2020).
55 Rosso, M. et al. Dendrite short-circuit and fuse effect on Li/polymer/Li cells. Electrochimica Acta 51, 5334-5340 (2006).
56 Qingwen, L. et al. Dendrite‐Free, High‐Rate, Long‐Life Lithium Metal Batteries with a 3D Cross‐Linked Network Polymer Electrolyte. Advanced Materials 29, 1604460, doi:doi:10.1002/adma.201604460 (2017).
57 Feng, S. et al. Single lithium-ion conducting polymer electrolytes based on poly [(4-styrenesulfonyl)(trifluoromethanesulfonyl) imide] anions. Electrochimica Acta 93, 254-263 (2013).
58 Rohan, R. et al. Functionalized polystyrene based single ion conducting gel polymer electrolyte for lithium batteries. Solid State Ionics 268, 294-299, doi:10.1016/j.ssi.2014.10.013 (2014).
59 Zhao, H. et al. Fumed silica-based single-ion nanocomposite electrolyte for lithium batteries. ACS applied materials & interfaces 7, 19335-19341 (2015).
60 Zhao, H. et al. Plasticized polymer composite single-ion conductors for lithium batteries. ACS applied materials & interfaces 7, 19494-19499 (2015).
61 Cao, C. et al. A solid-state single-ion polymer electrolyte with ultrahigh ionic conductivity for dendrite-free lithium metal batteries. Energy Storage Materials 19, 401-407 (2019).
62 Jeong, K., Park, S. & Lee, S.-Y. Revisiting polymeric single lithium-ion conductors as an organic route for all-solid-state lithium ion and metal batteries. Journal of materials chemistry A 7, 1917-1935 (2019).
63 Park, J.-H. et al. Close-packed poly (methyl methacrylate) nanoparticle arrays-coated polyethylene separators for high-power lithium-ion polymer batteries. Journal of power sources 196, 7035-7038 (2011).
64 Man, C. et al. Enhanced wetting properties of a polypropylene separator for a lithium-ion battery by hyperthermal hydrogen induced cross-linking of poly (ethylene oxide). Journal of Materials Chemistry A 2, 11980-11986 (2014).
65 Kim, K. J. et al. Ceramic composite separators coated with moisturized ZrO 2 nanoparticles for improving the electrochemical performance and thermal stability of lithium ion batteries. Physical Chemistry Chemical Physics 16, 9337-9343 (2014).
66 Li, Y., Li, Q. & Tan, Z. A review of electrospun nanofiber-based separators for rechargeable lithium-ion batteries. Journal of Power Sources 443, doi:10.1016/j.jpowsour.2019.227262 (2019).
67 Vlachou, M., Siamidi, A. & Kyriakou, S. in Electrospinning and Electrospraying-Techniques and Applications (IntechOpen, 2019).
68 Zhai, Y. et al. Sandwich-structured PVdF/PMIA/PVdF nanofibrous separators with robust mechanical strength and thermal stability for lithium ion batteries. Journal of Materials Chemistry A 2, 14511-14518 (2014).
69 Liu, J. et al. Lithium ion battery separator with high performance and high safety enabled by tri-layered SiO2@ PI/m-PE/SiO2@ PI nanofiber composite membrane. Journal of Power Sources 396, 265-275 (2018).
70 Wang, Z. et al. Competition Between the Plasticizer and Polymer on Associating with Li+ Ions in Polyacrylonitrile‐Based Electrolytes. Journal of the Electrochemical Society 144, 778 (1997).
71 Park, S.-R. et al. Cross-linked fibrous composite separator for high performance lithium-ion batteries with enhanced safety. Journal of Membrane Science 527, 129-136 (2017).
72 Lee, H., Yanilmaz, M., Toprakci, O., Fu, K. & Zhang, X. A review of recent developments in membrane separators for rechargeable lithium-ion batteries. Energy & Environmental Science 7, 3857-3886 (2014).
73 Li, W. et al. Hybrid gel polymer electrolyte fabricated by electrospinning technology for polymer lithium-ion battery. European Polymer Journal 67, 365-372 (2015).
74 Bard, A. J. & Faulkner, L. R. Fundamentals and applications. Electrochemical Methods 2, 580-632 (2001).
75 Dornbusch, D. A., Hilton, R., Gordon, M. J. & Suppes, G. J. Effects of sonication on eis results for zinc alkaline batteries. ECS Electrochemistry Letters 2, A89-A92 (2013).
76 Bruce, P. G., Hardgrave, M. T. & Vincent, C. A. The determination of transference numbers in solid polymer electrolytes using the Hittorf method. Solid State Ionics 53, 1087-1094 (1992).
77 Yang, M.-C. & Tong, J.-H. Loose ultrafiltration of proteins using hydrolyzed polyacrylonitrile hollow fiber. Journal of membrane science 132, 63-71 (1997).
78 Jassal, M., Bhowmick, S., Sengupta, S., Patra, P. K. & Walker, D. I. Hydrolyzed poly (acrylonitrile) electrospun ion-exchange fibers. Environmental engineering science 31, 288-299 (2014).
79 Li, Y., Li, Q. & Tan, Z. A review of electrospun nanofiber-based separators for rechargeable lithium-ion batteries. Journal of Power Sources 443, 227262 (2019).
80 Yang, M. & Hou, J. Membranes in lithium ion batteries. Membranes 2, 367-383 (2012).
81 Sun, X.-G. & Kerr, J. B. Synthesis and characterization of network single ion conductors based on comb-branched polyepoxide ethers and lithium bis (allylmalonato) borate. Macromolecules 39, 362-372 (2006).
82 Brissot, C., Rosso, M., Chazalviel, J.-N. & Lascaud, S. Dendritic growth mechanisms in lithium/polymer cells. Journal of power sources 81, 925-929 (1999).
83 Wang, S.-H., Kuo, P.-L., Hsieh, C.-T. & Teng, H. Design of poly (acrylonitrile)-based gel electrolytes for high-performance lithium ion batteries. ACS applied materials & interfaces 6, 19360-19370 (2014).
84 Zhang, M., Yu, S., Mai, Y., Zhang, S. & Zhou, Y. A single-ion conducting hyperbranched polymer as a high performance solid-state electrolyte for lithium ion batteries. Chemical Communications 55, 6715-6718 (2019).
85 Wen, T.-C., Wang, Y.-J., Cheng, T.-T. & Yang, C.-H. The effect of DMPA units on ionic conductivity of PEG–DMPA–IPDI waterborne polyurethane as single-ion electrolytes. Polymer 40, 3979-3988 (1999).
86 Zhao, Z. et al. A lithium carboxylate grafted dendrite-free polymer electrolyte for an all-solid-state lithium-ion battery. Journal of Materials Chemistry A 7, 25818-25823 (2019).
87 Zhuang, G. V. & Ross Jr, P. N. Analysis of the chemical composition of the passive film on Li-Ion battery anodes using attentuated total reflection infrared spectroscopy. Electrochemical and Solid State Letters 6, A136 (2003).
88 Ely, Y. E. & Aurbach, D. Identification of surface films formed on active metals and nonactive metal electrodes at low potentials in methyl formate solutions. Langmuir 8, 1845-1850 (1992).