LiCoPO4正極材料實際應用的主要問題是受限於相對較差的電子和離子傳導性，而離子摻雜被認為是改善固有電子和離子傳導性的重要策略。在本實驗中，通過溶膠-凝膠法合成的鐵鋅共摻雜LiCoPO4材料。XRD和Rietveld精修結果表明，鐵和鋅成功取代了LiCoPO4的鈷，而橄欖石結構卻沒有變。SEM結果可知，鐵和鋅摻雜不會導致材料的基本形貌發生變化，該材料由團聚的納米顆粒組成。EDX結果證實鐵和鋅是均勻分佈的。此外，相比未摻雜的LiCoPO4材料，鐵鋅共摻雜有效減輕了材料的極化現象，顯著提高了循環穩定性和變速率性能。
其中在1 C下，導電碳包覆的LiCo0.85Fe0.1Zn0.05PO4，初始電容量達到118.1 mAh/g ,100次循環容量保持率93.4 %,300圈後電容量仍有79 mAh/g。Randles – Sevcik方程式也表明在摻雜鐵的基礎上，少量鋅摻雜有效提高鋰離子的擴散速率。另外電化學阻抗譜(EIS)分析也可知，鋅的增加，內阻抗減小且在循環過程中內阻變化較小，這對電性穩定來說是有利的。但鋅的過量也會導致實際活物的減少，初始電容量有所下降，可能影響到鋰離子正常脫嵌。因此本實驗中得到鋅的摻雜應控制在5 %左右對電性改善最為有利。

Poor electronic and ionic conductivity are two main factors that limit the practical application of LiCoPO4 cathode materials. Ion doping is considered as an important strategy to improve the intrinsic electron and ion conductivity of LiCoPO4. In this word, a Fe-Zn co-doped LiCoPO4 cathode materials is synthesized using the sol-gel method. The results of X-ray powder diffraction (XRD) and Rietveld refinement indicate that the dopants were successfully introduced to the olivine lattice, while the olivine structure was not changed. Scanning electron microscope (SEM) images indicated that Fe and Zn doping do not cause changes in the basic morphology of the material and Energy dispersive spectroscopy (EDS) images confirmed that Fe and Zn are evenly distributed. In addition, compared with undoped LiCoPO4, the Fe-Zn co-doped LiCoPO4 reduces polarization, improves cycle stability and rate performance.
Notably, the carbon coated LiCo0.85Fe0.1Zn0.05PO4 delivers an initial discharge capacity of 118.1 mAh/g, shows a capacity retention of 93.4 % after 100 cycles and remained 79 mAh/g after 300 cycles at 1 C. The Randles-Sevcik equation also shows that a small amount of Zn doping improves the diffusivity of lithium ions on the basis of Fe doping. With the increase of Zn, the internal resistance decreases during the cycle, which is beneficial to electrical stability. However, the excessive amount of Zn would not only lead to the reduction of actual active material but also adversely affect the electrochemical performance of the electrode. Therefore, it is known that the substitution of Zn should be controlled at about 5 % in this experiment.

Abstract 1
摘要 2
致謝 3
目錄 4
第1章 緒論 7
1.1 鋰電池的發展與應用 7
1.2 磷酸鋰鈷電池的運作原理及優缺點 10
第2章 文獻回顧 14
2.1 磷酸鋰鈷材料的合成方法 14
2.2 電性改良方法 14
2.2.1 顆粒尺寸控制 14
2.2.1.1 減小顆粒尺寸 14
2.2.1.2 控制顆粒形貌 15
2.2.2 表面包覆改質 17
2.2.2.1 碳包覆 17
2.2.2.2 穩定化合物包覆 19
2.2.3 離子摻雜 21
第3章 實驗動機與步驟 27
3.1 研究動機 27
3.2 實驗藥品 27
3.3 材料製備 28
3.3.1 溶膠凝膠法合成LiCoPO4、LiCo0.9-xFe0.1ZnxPO4 (x = 0, 0.05, 0.10, 0.15) 28
3.3.2 導電碳包覆 29
3.4 電極製備 29
3.5 鈕扣電池組裝 30
3.6 材料與電化學分析 31
3.6.1 X光粉末繞射儀 31
3.6.2 場發式掃描電子顯微鏡 31
3.6.3 電池循環壽命測試 31
3.6.4 循環伏安法 31
3.6.5 電池循環壽命測試 32
3.6.6 TGA熱重分析儀 32
第4章 結果與討論 33
4.1 LiCoPO4/C與LiCo0.9-xFe0.1ZnxPO4/C（x = 0，0.05，0.1和0.15）之材料分析 33
4.1.1 LiCoPO4/C與LiCo0.9-xFe0.1ZnxPO4/C（x = 0，0.05，0.1和0.15）之相分析 33
4.1.2 碳包覆分析 36
4.1.3 形貌與元素分析 37
4.2 電性表現 39
4.2.1 循環壽命 39
4.2.2 變速率充放電表現 42
4.3 電化學分析 43
4.3.1 工作電壓平台 43
4.3.2 循環伏安法 45
4.3.3 利用循環伏安法討論擴散速率 48
4.3.4 交流阻抗分析 51
第5章 結論 54
第6章 參考文獻 55

[1] NOAA National Centers for Environmental Information, State of the Climate: Global Climate Report for January 2020, published online February 2020, retrieved on December 25, 2020 from https://www.ncdc.noaa.gov/sotc/global/
202001.
[2] https://dy.163.com/article/DTMM27KM05470JAD.html
[3] Diouf, Boucar, and Ramchandra Pode. "Potential of lithium-ion batteries in renewable energy." Renewable Energy 76 (2015): 375-380.
[4] Geoffroy Hautier, Anubhav Jain, Shyue Ping Ong, Byoungwoo Kang, Charles Moore, Robert Doe, and Gerbrand Ceder. "Phosphates as lithium-ion battery cathodes: an evaluation based on high-throughput ab initio calculations." Chemistry of Materials 23.15 (2011): 3495-3508.
[5] Christian M. Julien, Alain Mauger, Karim Zaghib and Henri Groult. "Comparative issues of cathode materials for Li-ion batteries." Inorganics 2.1 (2014): 132-154.
[6] Ling Fang, Huijuan Zhang, Yan Zhang, Li Liu, and Yu Wang. "Design and synthesis of two-dimensional porous Fe-doped LiCoPO4 nano-plates as improved cathode for lithium ion batteries." Journal of Power Sources 312 (2016): 101-108.
[7] Hanafusa, R., Y. Oka, and T. Nakamura. "Electrochemical and Magnetic Studies of Li-Deficient Li1-xCo1-xFexPO4 Olivine Cathode Compounds." Journal of The Electrochemical Society 162.2 (2014): A3045.
[8] Daniele Di Lecce, Jessica Manzi, Francesco M. Vitucci, Angela De Bonis, Stefania Panero, and Sergio Brutti. "Effect of the iron doping in LiCoPO4 cathode materials for lithium cells." Electrochimica Acta 185 (2015): 17-27.
[9] Borong Wu, Hongliang Xu, Daobin Mu, Lili Shi, Bing Jiang, Liang Gai, Lei Wang, Qi Liu, Liubin Ben, and Feng Wu. "Controlled solvothermal synthesis and electrochemical performance of LiCoPO4 submicron single crystals as a cathode material for lithium ion batteries." Journal of Power Sources 304 (2016): 181-188.
[10] Ni, Jiangfeng, Lijun Gao, and Li Lu. "Carbon coated lithium cobalt phosphate for Li-ion batteries: Comparison of three coating techniques." Journal of power sources 221 (2013): 35-41.
[11] Yuta Maeyoshi, Shohei Miyamoto, Yusaku Noda, Hirokazu Munakata, and Kiyoshi Kanamura."Effect of organic additives on characteristics of carbon-coated LiCoPO4 synthesized by hydrothermal method." Journal of Power Sources 337 (2017): 92-99.
[12] Allen, Jan L., T. Richard Jow, and Jeffrey Wolfenstine. "Improved cycle life of Fe-substituted LiCoPO4." Journal of Power Sources 196.20 (2011): 8656-8661.
[13] Wolfenstine, J. "Electrical conductivity of doped LiCoPO4." Journal of Power Sources 158.2 (2006): 1431-1435.
[14] N. V. Kosova, O. A. Podgornova, E. T. Devyatkina, V. R. Podugolnikov and S. A. Petrov. "Effect of Fe2+ substitution on the structure and electrochemistry of LiCoPO4 prepared by mechanochemically assisted carbothermal reduction." Journal of Materials Chemistry A 2.48 (2014): 20697-20705.
[15] Lucangelo Dimesso, Christina Spanheimer, Mathis M. Mueller, Hans-Joachim Kleebe,and Wolfram Jaegermann. "Properties of Ca-containing LiCoPO4-graphitic carbon foam composites." Ionics 21.8 (2015): 2101-2107.
[16] Dimesso, Lucangelo, Christina Spanheimer, and Wolfram Jaegermann. "Investigation of the LiCo1−xMgxPO4 (0 ≤ x ≤ 0.1)–graphitic carbon foam composites." Solid State Sciences 30 (2014): 89-93.
[17] Jiang Feng Ni, Yuhai Han, Jianzhong Liu, Haibo Wang, and Lijun Gao. "Improving electrochemical properties of LiCoPO4 by Mn substitution: A case research on LiCo0. 5Mn0. 5PO4." ECS Electrochemistry Letters 2.1 (2012): A3.
[18] Karl J. Kreder, III, Gaurav Assat, and Arumugam Manthiram. "Aliovalent substitution of V3+ for Co2+ in LiCoPO4 by a low-temperature microwave-assisted solvothermal process." Chemistry of Materials 28.6 (2016): 1847-1853.
[19] Huanhuan Li, Yaping Wang a, Xiaoliang Yang, Liang Liu, Long Chen, and Jinping Wei. "Improved electrochemical performance of 5 V LiCoPO4 cathode materials via yttrium doping." Solid State Ionics 255 (2014): 84-88.
[20] Jan L. Allen, Joshua L. Allen, Travis Thompson, Samuel A. Delp, Jeff Wolfenstine,and T. Richard Jow. "Cr and Si Substituted-LiCo0. 9Fe0. 1PO4: Structure, full and half Li-ion cell performance." Journal of Power Sources 327 (2016): 229-234.
[21] Jennifer Ludwig, Cyril Marino, Dominik Haering, Christoph Stinner, Hubert A. Gasteiger, and Tom Nilges. "Controlling the shape of LiCoPO4 nanocrystals by supercritical fluid process for enhanced energy storage properties." Scientific reports 4.1 (2014): 1-8.
[22] Yue Wang, Jingyi Qiu, Zhongbao Yu, Hai Ming, Meng Li, Songtong Zhang, and Yusheng Yang. "AlF3-modified LiCoPO4 for an advanced cathode towards high energy lithium-ion battery." Ceramics International 44.2 (2018): 1312-1320.
[23] Örnek, Ahmet. "An impressive approach to solving the ongoing stability problems of LiCoPO4 cathode: Nickel oxide surface modification with excellent core–shell principle." Journal of Power Sources 356 (2017): 1-11.
[24] Dimesso, Lucangelo, Christina Spanheimer, and Wolfram Jaegermann. "Investigation of the LiCo1−xMgxPO4 (0⩽ x⩽ 0.1) system." Journal of alloys and compounds 582 (2014): 69-74.
[25] Stefan Michael Rommel, Jan Rothballer, Norbert Schall, Christian Brünig, and Richard Weihrich. "Characterization of the carbon-coated LiNi1−yCoyPO4 solid solution synthesized by a non-aqueous sol-gel route." Ionics 21.2 (2015): 325-333.
[26] Örnek, Ahmet, Mustafa Can, and Ali Yeşildağ. "Improving the cycle stability of LiCoPO4 nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution." Materials Characterization 116 (2016): 76-83.
[27] Yue Wang, Junhong Chen, Jingyi Qiu, Zhongbao Yu, Hai Ming, Meng Li, Songtong Zhang, and Yusheng Yang. "Cr-substituted LiCoPO4 core with a conductive carbon layer towards high-voltage lithium-ion batteries." Journal of Solid State Chemistry 258 (2018): 32-41.
[28] Fei Wang, Jun Yang, Yanna NuLi, and Jiulin Wang."Highly promoted electrochemical performance of 5 V LiCoPO4 cathode material by addition of vanadium." Journal of Power Sources 195.19 (2010): 6884-6887.
[29] Slater, John C. "Atomic radii in crystals." The Journal of Chemical Physics 41.10 (1964): 3199-3204.
[30] J. G. Lapping, O. J. Borkiewicz, K. M. Wiaderek, J. L. Allen, T. R. Jow, and J. Cabana. "Structural Changes and Reversibility Upon Deintercalation of Li from LiCoPO4 Derivatives." ACS Applied Materials & Interfaces 12.18 (2020): 20570-20578.
[31] Koleva, Violeta, Ekaterina Zhecheva, and Radostina Stoyanova. "Ordered Olivine‐Type Lithium–Cobalt and Lithium–Nickel Phosphates Prepared by a New Precursor Method." European Journal of Inorganic Chemistry 2010.26 (2010): 4091-4099.
[32] Jian-Nan Zhu, Wen-Cui Li, Fei Cheng and An-Hui Lu. "Synthesis of LiMnPO4/C with superior performance as Li-ion battery cathodes by a two-stage microwave solvothermal process." Journal of Materials Chemistry A 3.26 (2015): 13920-13925.