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研究生： 黃建荺
Huang, Chien-Yun
論文名稱： 共摻雜鐵、鈷、鎂來改善磷酸鋰錳作為鋰離子電池陰極材料的電化學表現
Improved Electrochemical Performance of LiMnPO4 as Cathode Material for Li Ion Battery by co-doping Fe-Co-Mg
指導教授： 蔡哲正
Tsai, Cho-Jen
口試委員: 林居南
Lin, Jiu-Nan
陳翰儀
Chen, Han-Yi
學位類別： 碩士
Master
系所名稱： 工學院 - 材料科學工程學系
Materials Science and Engineering
論文出版年： 2018
畢業學年度： 106
語文別： 中文
論文頁數： 47
中文關鍵詞： 鋰離子電池 、磷酸鋰錳 、共摻雜
外文關鍵詞： LiMnPO4, co-doping, Li-ion battery
相關次數： 點閱：3  下載：0 
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    • 本研究嘗試在水熱法合成的磷酸鋰錳中共摻雜鐵-鈷-鎂，以改變Li-O鍵結能和創造鋰缺陷，來使鋰離子傳導性更好。實驗結果為共摻雜鐵-鈷-鎂在高速率充放電有最好的表現，甚至比共摻雜鐵-鈷或鐵-鎂還要更好。XPS結果也顯示共摻雜鐵-鈷-鎂有最強的Mn-O和P-O鍵，因此Li-O鍵會相對變弱，鋰離子就能更快的嵌入脫出。至於循環壽命則是依據摻雜的鎂和鈷之比例而有不同的表現，共摻雜鐵-鈷有最高的電容量，而隨著鎂的量越多，電容量逐漸下降，因此共摻雜鐵-鎂的電容量為最低。不過穩定性的趨勢卻是相反的，隨著鎂的量越多，電容量的衰退幅度越小。綜合來說，共摻雜鐵-鈷-鎂在高速率充放電的協同作用比摻雜鐵-鈷和鐵-鎂還要明顯，而在0.5 C的循環壽命表現則與鈷/鎂的比例有關。

    In this study, we synthesize lithium manganese phosphate co-doped Fe-Co-Mg by solvothermal method. Co-doping Fe-Co-Mg can change the binding energy and create Li vacancy, so lithium ions insert and extract faster. We also discuss co-doping effect of three conditions: Fe-Co, Fe-Mg and Fe-Co-Mg. The result shows that the cases of co-doping Fe-Co-Mg have better rate capability than the case of co-doping Fe-Co and Fe-Mg. According to XPS results, the cases of co-doping Fe-Co-Mg have stronger Mn-O bonds and P-O bonds than that of co-doping Fe-Co and Fe-Mg. It causes Li-O bonds become weaker, so lithium ions can insert/extract faster. As for cycle life, the case of co-doping Fe-Co has the highest initial capacity. The initial capacity decreases depending on the amount of Mg. The decrease of the initial capacity depends on the amount of Mg. Doping more Mg and less Co decrease the initial capacity. However, the trend of stability of cycle life is opposite. The cycle life decays more slowly with increasing amount of Mg doped.
    To sum up, co-doping three elements shows more significant synergistic effect about rate capability than co-doping two elements does.

    Abstract……………………………………………………………………………….1 摘要……………………………………………………………………………………2 致謝……………………………………………………………………………………3 目錄……………………………………………………………………………………4 圖目錄…………………………………………………………………………………5 表目錄…………………………………………………………………………………6 第一章 緒論…………………………………………………………………………7 1.1鋰離子電池發展概況……………………………………………………7 1.2磷酸鋰錳電池的運作原理及優缺點………………………………10 第二章 文獻回顧……………………………………………………………………12 2.1 合成方法………………………………………………………………12 2.1.1 磷酸鋰錳常見的合成方法……………………………………..12 2.1.2 水熱法…………………………………………………………..12 2.2 改善形貌……………………………………………………………….12 2.2.1 界面活性劑……………………………………………………..12 2.2.2 pH值…………………………………………………………….14 2.3 離子摻雜……………………………………………………………….16 第三章 實驗步驟與動機……………………………………………………………20 3.1 研究動機……………………………………………………………….20 3.2 實驗藥品……………………………………………………………….21 3.3 材料製備……………………………………………………………….21 3.3.1 水熱法合成LiMnPO4、LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)………………………………………………..21 3.3.2 碳包覆…………………………………………………………..22 3.4 極片製備……………………………………………………………….22 3.5鈕扣電池組裝…………………………………………………………..23 3.6 材料與電化學分析…………………………………………………….23 3.6.1 X光粉末繞射儀………………………………………………...23 3.6.2 場發式掃描電子顯微鏡………………………………………..23 3.6.3 TGA熱重分析儀………………………………………………..24 3.6.4 電池循環壽命測試……………………………………………..24 3.6.5 循環伏安法……………………………………………………..24 3.6.6 交流阻抗分析…………………………………………………..24 3.6.7 X-ray光電子能譜分析……………………………………….....25 第四章 結果與討論…………………………………………………………………25 4.1 LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)之材料分析………………………………………………………………..25 4.1.1 LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)相分析………………………………………………………25 4.1.2 碳包覆分析……………………………………………………..27 4.1.3 形貌分析………………………………………………………..29 4.1.4 XPS分析………………………………………………………...31 4.2 電性表現……………………………………………………………….33 4.2.1 循環壽命………………………………………………………..33 4.2.2 變速率充放電表現……………………………………………..35 4.3 電化學分析…………………………………………………………….36 4.3.1 工作電壓平台…………………………………………………..36 4.3.2 循環伏安法……………………………………………………..37 4.3.3 利用循環伏安法討論擴散速率………………………………..39 4.3.4 交流阻抗分析…………………………………………………..42 第五章 結論…………………………………………………………………………45 第六章 參考文獻……………………………………………………………………46 圖目錄 圖1.1 近年來二氧化碳濃度和年均溫關係圖………………………………………8 圖1.2、智慧電網示意圖……………………………………………………………..8 圖1.3、電動汽車示意圖……………………………………………………………..9 圖1.4、二次電池能量密度比較圖…………………………………………………..9 圖1.5、不同晶體結構於工作時的放熱比較圖……………………………………..9 圖1.6、各種磷酸鋰鹽工作電壓及理論電容量圖…………………………………11 圖1.7、磷酸鋰鹽橄欖石晶體結構示意圖…………………………………………11 圖2.1、不同EG/H2O比例之形貌(a) 11/1 (b) 2/1 (c) 1/1 (d) 0/1………………….13 圖2.2、不同形貌之變速率充放電表現(a)11/1 (b)2/1……………………………..13 圖2.3、水熱中加入P123作為碳源和界面活性劑的製成示意圖………………..14 圖2.4、不同碳源的阻抗差異………………………………………………………14 圖2.5、不同加入順序以及pH值對形貌的影響示意圖………………………….15 圖2.6、不同形貌之便速率充放電表現……………………………………………15 圖2.7、共摻雜和單一摻雜的阻抗分析……………………………………………17 圖2.8、循環伏安法下不同掃描速率與電流峰值之關係…………………………17 圖2.9、摻雜鐵和鈦之循環壽命比較…………………..…………………………..18 圖2.10、鉻的不同摻雜量對阻抗和擴散係數的影響……………………………..18 圖2.11、鉻的不同摻雜量之循環壽命……………………………………………..19 圖2.12、不同鐵鎳摻雜量之(a)變速率充放電表現 (b)循環壽命………………...19 圖4.1、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1) XRD圖……………………………………………………………………………26 圖4.2、TOPAS計算出之晶格常數與晶格體積比較圖…………………………...27 圖4.3、碳包覆前後的XRD圖…………………………………………………….28 圖4.4、包覆碳之磷酸鋰錳的TGA圖……………………………………………..29 圖4.5、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)之形貌比較………………………………………………………………………30 圖4.6、摻雜不同元素之錳的2p軌域鍵結能……………………………………..32 圖4.7、錳的2p3/2軌域鍵結能變化………………………………………………...33 圖4.8、磷的2p軌域鍵結能變化…………………………………………………..33 圖4.9、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)0.5 C之循環壽命表現圖…………………………………..…..……….………..34 圖4.10、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)之10 C循環壽命表現圖…………………………………………………….….35 圖4.11、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)之變速率充放電表現圖………………………………………………………..36 圖4.12、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)之第一圈循環電壓平台圖……………………………………………………..37 圖4.13、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)之CV曲線(掃描速率0.1 mV/s)…………………………………………….38 圖4.14、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)在不同掃描速率下之CV曲線………………………………………………..40 圖4.15、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)在不同掃描速率對應之電流峰值圖…………………………………………..41 圖4.16、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)電池循環前之Nyquist圖……………………………………………………...43 圖4.17、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)電池循環三圈後之Nyquist圖………………………………………………...43 圖4.18、LiMnPO4與LiMn0.8Fe0.1Co1-xMgxPO4 (x = 0, 0.025, 0.05, 0.075, 0.1)電池循環150圈後之Nyquist圖……………………………………………...44 表目錄 表2.1、不同加入順序以及pH值對形貌的影響………………………………….15 表2.2、摻雜鐵或鈦對晶體常數的影響……………………………………………18 表2.3、各文獻之循環表現比較表…………………………………………………20 表3.1、本實驗使用之化學藥品……………………………………………………21 表4.1、氧八面體結構中的過渡金屬離子半徑……………………………………26 表4.2、晶格常數與體積……………………………………………………………27 表4.3、CV測試的充放電電壓與極化之比較…….………………………………39 表4.4、圖4.15之對應斜率表……………………………………………………...41

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