鋰硫電池被視為未來潛藏的能源儲存系統，因為它擁有極高的理論電容量 (1672 mAh/g)，但是因為穿梭現象，多硫化物會溶解到電解液中使循環壽命變差。本篇論文使用導電高分子塗佈在多孔性碳球來提升鋰硫電池的效能，導電高分子塗佈層可以抑制充放電過程中產生的多硫化物，避免溶解到電解液中，本研究合成設計一個擁有親水和疏水兩性性質的高分子，能夠形成孔洞型態佳的多孔微球，再將其碳化成多孔碳球，而製備出來的多孔碳球提供空間容納和分散硫，以改善硫本身導電性不佳以及體積膨脹的問題。結合兩者材料可以提升硫的利用率，讓鋰硫電池有更高的電容量，並且減緩多硫化物溶解到電解液中，可以改善電池的循環壽命。利用紅外線光譜儀和掃描式電子顯微鏡證明導電高分子成功塗佈到硫-多孔碳球材料上，以熱重分析儀可以測量硫-導電高分子/多孔碳球實際的硫含量，也間接確認導電高分子成功塗佈於多孔碳球上。最後電化學測量的部分，在充放電測試的部分，在放電速率0.05 C下電容量1234 mAh/g (硫-導電高分子/多孔碳球) 比電容量1110 mAh/g (硫) 來的好。在循環壽命的部分，經 0.5 C，100次充放電擁有48.12% (硫-導電高分子/多孔碳球) 仍比20.20% (硫) 明顯改善許多，電化學結果證明了導電高分子/多孔碳球能夠增加硫的利用率和改善循環壽命。

Lithium-sulfur batteries are considered a great prospect for energy storage purpose, courtesy to high theoretical specific capacity of sulfur (1672 mAh/g). However, due to shuttling effect of lithium polysulfides, these batteries show poor cycle life. In this study, to improve the performance, conductive polymers and porous carbon spheres are used. While the nitrogen atom of conductive polymers can bind polysulfides during charging and discharging, the porous carbon spheres with high quality of morphologies can provide better space to improve poor conductivity and expansion of sulfur. Higher capacity and better cycle life are achieved by the synergic effect of both the materials as it increases the utilization of sulfur and prevents the dissolution of polysulfides in the electrolyte. The sulfur-conductive polymers/porous carbon spheres composite material is characterized by infrared spectroscopy and scanning electron microscope. The sulfur content is quantified by thermogravimetric analysis. Electrochemical measurements show a better discharge capacity for the synthesized composite electrode (1234 mAh/g) compared to the blank sulfur composite electrode (1110 mAh/g), at a 0.05C- discharging rate. The cycle life of the composite electrode is also better than that of the blank. The results demonstrate that the composite electrode material can improve the performance of lithium-sulfur battery.

目錄

論文審定書 i
論文公開授權書 ii
誌謝 iii
摘要 v
ABSTRACT vi
目錄 vii
圖次 x
表次 xiii
第一章 緒論 1
1.1 前言 2
1.2 研究動機 3
第二章 文獻回顧 4
2.1 鋰離子電池 5
2.1.1 工作原理 5
2.1.2 正極材料 6
2.2 鋰硫電池 10
2.2.1 工作原理 10
2.2.2 挑戰 12
2.2.3 改善方法 13
2.3 多孔材料 16
2.3.1 簡介 16
2.3.2 溶劑揮發法 17
2.3.3 多孔微球形成機制 18
第三章 實驗藥品與儀器 19
3.1 實驗藥品 20
3.2 儀器型號 23
3.3 儀器型號與實驗條件 24
第四章 實驗步驟 28
4.1 以 NMR 鑑定 poly(vinylbenzyl chloride) 的結構 29
4.1.1 單體水解/醇解速率比較 29
4.1.2 單體經不同時間水解/醇解再進行聚合反應 30
4.1.3 觀察以 AIBN 為起始劑合成的 poly(vinylbenzyl chloride) 在溶劑中水解/醇解的狀況 30
4.1.4 觀察以 AIBA 為起始劑聚合成的 poly(vinylbenzyl chloride) 高分子在溶劑中水解/醇解的狀況 31
4.1.5 不同聚合時間的 poly(vinylbenzyl chloride) 31
4.2 正極材料改善方法 32
4.2.1 合成 poly(styrene-co-vinylbenzyl chloride) 32
4.2.2 製備多孔碳球 32
4.2.3 製備硫-多孔碳球複合材料 33
4.2.4 純化吡咯 33
4.2.5 製備硫-導電高分子/多孔碳球複合材料 33
4.2.6 混漿 34
4.2.7 組成電池 35
第五章 結果與討論 36
5.1 以液態核磁共振光譜計算單體水解/醇解狀況 37
5.2 PVBC化學特性 41
5.3 多孔微球塗佈導電高分子聚吡咯之掃描式電子顯微鏡圖 46
5.4 傅立葉轉換紅外線光譜分析 47
5.5 熱重分析 49
5.6 循環伏安法 (Cyclic Voltammetry) 50
5.7 定電流充放電 (C-rate test) 52
5.8 循環壽命測試 (Cycle Life) 55
5.9 材料結構掃描式電子顯微鏡檢測 57
第六章 結論 60
第七章 參考文獻 62
第八章 附錄 68

圖次
圖 1 鋰離子二次電池工作原理 5
圖 2 鋰離子電池結構示意圖 6
圖 3 鈷酸鋰之層狀結構示意圖 7
圖 4 錳酸鋰之尖晶石結構示意圖 8
圖 5 磷酸鋰鐵之橄欖石結構示意圖 8
圖 6 鋰硫電池結構 10
圖 7 鋰硫電池之 (a) 放電曲線圖和 (b) 硫的還原機制 11
圖 8 Nazar 團隊於 2009 年發表的高度有序 CMK-3 材料 13
圖 9 將導電高分子塗佈於中空的奈米硫球 14
圖 10 將二氧化鈦塗佈在硫奈米粒子再利用甲苯將些許硫溶解掉，以得到蛋黃殼形態 15
圖 11 電荷穩定示意圖 17
圖 12 立體穩定示意圖 18
圖 13 多孔微球形成示意圖 18
圖 14 單體水解/醇解速率比較 29
圖 15 以不同時間水解/醇解單體再進行聚合反應 30
圖 16 觀察以 AIBN 為起始劑合成的 poly(vinylbenzyl chloride) 在溶劑中水解/醇解的狀況 30
圖 17 觀察以 AIBA 為起始劑聚合成的 poly(vinylbenzyl chloride) 高分子在溶劑中水解/醇解的狀況 31
圖 18 合成 poly (styrene-co-vinylbenzyl chloride) 32
圖 19 鈕扣型電池組件圖 35
圖 20 單體 VBC 之 1H NMR 圖譜 37
圖 21 單體 VBC 水解/醇解 2 小時之 1H NMR 圖譜 38
圖 22 單體 VBC 經不同時間水解/醇解的 1H NMR 圖譜疊圖 (a) 0 小時、(b) 2 小時、(c) 4 小時、(d) 8 小時、(e) 12 小時、(f) 16 小時 39
圖 23 VBC、VBA、VBEE 不同水解/醇解時間的莫耳比例圖 40
圖 24 以 AIBN 為起始劑、THF 為溶劑聚合 16 小時得到的 PVBC 再水解/醇解 8 小時之 1H NMR 圖譜 42
圖 25 以 AIBA 為起始劑聚合 8 小時 PVBC 之 1H NMR 圖譜 43
圖 26 以 AIBA 為起始劑聚合 8 小時 PVBC 再水解/醇解 8 小時 之 1H NMR 圖譜 44
圖 27 單體 VBC 水解/醇解的速率及經不同時間聚合的轉換率比較 45
圖 28 導電高分子/多孔微球之掃描式電子顯微鏡圖 46
圖 29 硫-多孔碳球、硫-導電高分子/多孔碳球、導電高分子之紅外線光譜圖 47
圖 30 硫-導電高分子/多孔碳球及硫-多孔碳球熱重分析圖 49
圖 31 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|polypyrrole/porous carbon spheres (以 Guar Gum 為黏著劑) (b) 只用Polypyrrole 作為正極材料測量循環伏安法 50
圖 32 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur-polypyrrole/porous carbon spheres (b) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur (以 PVDF 為黏著劑) 電池之循環伏安法圖 51
圖 33 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur-polypyrrole/porous carbon spheres (b) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur (以 Guar Gum 為黏著劑) 電池之循環伏安法圖 51
圖 34 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur-polypyrrole/porous carbon spheres (b) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur (以 PVDF 為黏著劑) 電池之充放電圖 52
圖 35 以 sulfur-polypyrrole/porous carbon spheres 和 sulfur 作為正極材料 (以 PVDF 為黏著劑) 比較不同放電速率之電容量圖 53
圖 36 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur-polypyrrole/porous carbon spheres (b) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur (以 Guar Gum 為黏著劑) 電池之充放電圖 54
圖 37 以 sulfur-polypyrrole/porous carbon spheres 和 sulfur 作為正極材料 (以 Guar Gum 為黏著劑) 比較不同放電速率之電容量圖 54
圖 38 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur-polypyrrole/porous carbon spheres (b) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur (以 PVDF 為黏著劑) 電池之循環壽命圖 55
圖 39 (a) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur-polypyrrole/porous carbon spheres (b) Li|Celgard®2500/1 M LiTFSI (DME/DOL)|sulfur (以 Guar Gum 為黏著劑) 電池之循環壽命圖 56
圖 40 多孔碳球之掃描式電子顯微鏡圖 57
圖 41 導電高分子/多孔碳球之掃描式電子顯微鏡圖 58
圖 42 正極材料之掃描式電子顯微鏡圖 58
圖 43 組裝成電池後沒有經過電化學測試立即拆開之掃描式電子顯微鏡圖 59
圖 44 電池測試完循環壽命之掃描式電子顯微鏡圖 59

表次
表 1 鋰離子電池之正極材料比較 9
表 2 實驗藥品 20
表 3 儀器型號 23
表 4 單體VBC、PVBC16h (AIBN)、PVBC8h (AIBA) 醇解速率比較表 44
表 5 硫-導電高分子/多孔碳球、聚吡咯紅外線光譜比較表 48
表 6 以 PVDF及Guar Gum 為黏著劑，硫-導電高分子/多孔碳球和硫作為正極材料電池之循環壽命結果比較 56

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