因鋰離子電池具有能量密度高、放電容量大、循環壽命長、安全性好等特點，成為最有希望的儲能材料之一。其中LiCoPO4因具有高的氧化還原電壓4.8 V和能量密度800 Wh/kg被大量研究。但LiCoPO4也有一些不足之處，電子導電率低，鋰離子傳導率低，電解液在高壓下易分解導致循環電性差。
本實驗用水熱法製備LiCoPO4粉末，分別在220 oC下的溶劑熱法和400 oC下的超臨界流體法兩個體系，并摻雜三價鐵以期改善電性。將三價鐵代替鈷的位置能使材料中多出鋰離子的缺陷，增加鋰離子的擴散速率。
超臨界流體法製備的LiCoPO4顆粒遠小於溶劑熱法製備的，且多片狀結構。在0.1 C下，摻雜10%三價鐵確實能使放電電容量提升一倍。但不如預期的是還沒找到一種合適的方法使片狀結構的LiCoPO4測出實際的電性。

Lithium ion batteries are considered to be one of the most promising energy storage materials because of their high energy density, high discharge capacity, long cycle life and safety. LiCoPO4 cathode material attracts lots of research interests due to high redox potential ( 4.8 V ) and high energy density ( 800 Wh/kg ). However, there are some shortcomings, such as, low electronic conductivity, low lithium ion conductivity, and the decomposition of electrolytes under high potentials, resulting in poor cyclic stability.
LiCoPO4 particles were prepared by hydrothermal method. The syntheses were explored in two conditions: solvothermal process at 220 oC and supercritical fluid method at 400 oC. Fe3+ doping was also conducted in order to improve the electrical performance of LiCoPO4.
LiCoPO4 particles prepared by supercritical fluid method were much smaller than those prepared by solvothermal method, which mainly have sheet structures. Although, poor electrochemical performance were obtained in this experiment due to non-optimized slurry forming processing, Fe3+ doping actually improved the discharge capacity slightly.

Abstract i
摘要 ii
目錄 iii
圖目錄 vii
表目錄 xiv
第一章 緒論 1
1.1 電池的重要性 1
1.2 電池的種類 3
1.3 鋰離子電池陰極材料 3
1.4 鋰離子電池的工作原理 5
1.5 聚陰離子型電池材料 6
1.6 研究動機 6
第二章 文獻回顧 9
2.1 材料結構 9
2.2 電性特征 9
2.3 材料優點及缺點 11
2.4 電性改良方法 13
2.4.1 顆粒尺寸控制 13
2.4.1.1 減小顆粒尺寸 13
2.4.1.2 控制表面形貌 14
2.4.2 摻雜 17
2.4.2.1 Co位摻雜 17
2.4.2.2 Li位摻雜 18
2.4.3 碳包覆 21
2.5 合成方法 24
2.5.1 水熱法 24
2.5.2 溶膠凝膠法 25
2.5.3 固相反應法 25
第三章 實驗步驟 26
3.1 材料製備 26
3.1.1 低溫溶劑熱法 26
3.1.2 超臨界流體法 27
3.2 材料鑒定分析 28
3.2.1 X-ray繞射分析 28
3.2.2 掃描式電子顯微鏡 29
3.2.3 粒徑分析 29
3.2.4 熱重/熱差分析 29
3.3 陰極製備 29
3.4 電池製備 30
3.5 電性測試 30
3.5.1 循環壽命測試 30
3.5.2 循環伏安測試 31
3.5.3 交流阻抗測試 31
第四章 結果與討論 32
4.1 低溫溶劑熱法下調變不同參數對LiCoPO4粉末相、大小和表面形貌的影響 32
4.1.1 冷卻方式對LiCoPO4粉末相、大小和表面形貌的影響 32
4.1.2 不同鋰源對LiCoPO4粉末相、大小和表面形貌的影響 33
4.1.3 不同鈷源對LiCoPO4粉末相、大小和表面形貌的影響 34
4.1.4 乙醇的比例對LiCoPO4粉末相、大小和表面形貌的影響 36
4.1.5 反應溫度對LiCoPO4粉末相、大小和表面形貌的影響 38
4.1.6 反應時間對LiCoPO4粉末相、大小和表面形貌的影響 40
4.1.7 油胺對LiCoPO4粉末相、大小和表面形貌的影響 43
4.1.8 pH值對LiCoPO4粉末相、大小和表面形貌的影響 44
4.1.9 不同表面活性劑對LiCoPO4粉末相、大小和表面形貌的影響 46
4.2 超臨界流體法下調變不同參數對LiCoPO4粉末相、大小和表面形貌的影響 48
4.2.1 400 oC下反應時間對LiCoPO4粉末相、大小和表面形貌的影響 48
4.2.2 350 oC下反應時間對LiCoPO4粉末相、大小和表面形貌的影響 51
4.2.3 油胺濃度對LiCoPO4粉末相、大小和表面形貌的影響 54
4.2.4 LiCoPO4源材料濃度對LiCoPO4粉末相、大小和表面形貌的影響 56
4.2.5 溶質濃度對LiCoPO4粉末相、大小和表面形貌的影響 58
4.2.6 溶液總體積對LiCoPO4粉末相、大小和表面形貌的影響 60
4.3 用超臨界流體法合成的LiCoPO4 / C粉末的電性表現 62
4.4 超臨界流體法下摻雜Fe3+對LiCoPO4粉末的影響 63
4.5 調變包覆碳的不同參數對LiCoPO4 / C粉末電性的影響 69
4.5.1 不同包覆碳的方式對LiCoPO4 / C粉末電性的影響 69
4.5.2 不同碳源對LiCoPO4 / C粉末電性的影響 70
4.5.3 不同碳化溫度對LiCoPO4 / C粉末電性的影響 71
4.5.4 不同碳含量對LiCoPO4 / C粉末電性的影響 72
4.6 調變塗佈的不同參數對LiCoPO4 / C粉末電性的影響 73
第五章 結論 76
第六章 參考文獻 77

[1] Climate Change 2014: Mitigation of Climate Change, IPCC, 2014.
[2] Alexander Kraytsberg and Yair Ein - Eli, Higher, stronger, better… A Review of 5 Volt Cathode Materials for Advanced Lithium - Ion Batteries, Advanced Energy Materials, 2012, 2, 922 - 939.
[3] Naoki Nitta and Feixiang Wu et al, Li - ion battery materials: present and future, Materials Today, June 2015, Volume 18, Number 5.
[4] Zhengliang Gong and Yong Yang, Recent advances in the research of polyanion - type cathode materials for Li - ion batteries, Energy Environmental Science, 2011, 4, 3223 - 3242.
[5] L. Dimesso and C. Forster et al, Developments in nanostructured LiMPO4 ( M = Fe, Co, Ni, Mn ) composites based on three dimensional carbon architecture, Chem. Soc. Rev., 2010, 41, 5068 - 5080.
[6] 倪江峰和周恆輝等, 鋰離子電池正極材料LiMPO4的研究進展, 化學進展, 2004年7月, 第16卷第4期, 554 - 560.
[7] Boucar Diouf and Ramchandra Podel, Potential of lithium - ion batteries in renewable energy, Renewable Energy, 2015, 76, 375 - 380.
[8] C. M. Julien and A. Mauger, Review of 5 - V electrodes for Li - ionbatteries: status and trends, Ionics, 2013, 19: 951 - 988.
[9] 鄧玲, 新型磷酸鈷鋰正極材料的合成與電化學性能, 上海應用技術學院, 2015年5月.
[10] Adrien Boulineau and Thibaut Gutel, Revealing Electrochemically Induced Antisite Defects in LiCoPO4: Evolution upon Cycling, Chemistry of Materials, 2015, 27, 802 - 807.
[11] Quang Duc Truong and Murukanahally Kempaiah Devaraju et al, Controlling the shape of LiCoPO4 nanocrystals by supercritical fluid process for enhanced energy storage properties, SCIENTIFIC REPORTS, 2014, 4: 3975, DOI: 10. 1038 / srep03975, 1 - 8.
[12] Meng Hu and Xiaoli Pang et al, Recent progress in high - voltage lithium ion batteries, Journal of Power Sources, 2013, 237, 229 - 242.
[13] Bramnik NN and Nikolowski K et al, Thermal stability of LiCoPO4 cathodes, Electrochem Solid - State, 2008, Lett 11: A 89 - A 93.
[14] Murukanahally Kempaiah Devaraju and Quang Duc Truong et al, Antisite defects in LiCoPO4 nanocrystals synthesized via a supercritical fluid process, RSC Advances, 2014, 4, 52410 - 52414.
[15] Borong Wu and Hongliang Xu et al, Controlled solvothermal synthesis and electrochemical performance of LiCoPO4 submicron single crystals as a cathode material for lithium ion batteries, Journal of Power Sources, 2016, 304, 181 - 188.
[16] Murukanahally Kempaiah Devaraju and Dinesh Rangappa et al, Controlled synthesis of plate - like LiCoPO4 nanoparticles via supercritical method and their electrode property, Electrochimica Acta, 2012, 85, 548 - 553.
[17] Xiang Huang and Junfeng Ma et al, Hydrothermal synthesis of LiCoPO4 cathode materials for rechargeable lithium ion batteries, Materials Letters, 2005, 59, 578 - 582.
[18] Reginald E. Rogers and Garry M. Clarke et al, Impact of microwave synthesis conditions on the rechargeable capacity of LiCoPO4 for lithium ion batteries, J Appl Electrochem, 2013, 43: 271 - 278.
[19] Christoph Neef and Hans - Peter Meyer et al, Morphology - controlled two - step synthesis and electrochemical studies on hierarchically structured LiCoPO4, Solid Sciences, 2015, 48, 270 - 277.
[20] Xianhong Rui and Xiaoxu Zhao et al, Olivine - Type Nanosheets for Lithium Ion Battery Cathodes, ACS NANO, 2013, VOL. 7, NO. 6, 5637 - 5646.
[21] Murukanahally Kempaiah Devaraju and Quang Duc Truong et al, Supercritical Fluid Synthesis of LiCoPO4 Nanoparticles and Their Application to Lithium Ion Battery, Inorganics, 2014, 2, 233 - 247.
[22] R. Hanafusa and Y. Oka et al, Electrochemical and Magnetic Studies of Li - Deficient Li1-xCo1-xFexPO4 Olivine Cathode Compounds, Journal of The Electrochemical Society, 2015, 162 ( 2 ) , 3045 - 3051.
[23] Li Liu and Huijuan Zhang et al, Unique synthesis of sandwiched graphene@(Li0.893Fe0.036)Co(PO4) nanoparticles as high - performance cathode materials for lithium - ion batteries, Journal of Materials Chemistry A, 2015, 3, 12320 - 12327.
[24] Daniele Di Lecce and Jessica Manzi et al, Effect of the iron doping in LiCoPO4 cathode materials for lithium cells, Electrochimica Acta, 2015, 185, 17 - 27.
[25] Jiang Feng Ni and Yuhai Han et al, Improving Electrochemical Properties of LiCoPO4 by Mn Substitution: A Case Research on LiCo0.5Mn0.5PO4, ECS Electrochemistry Letters, 2013, 2 ( 1 ) , A 3 - A 5.
[26] Daniele Di Lecce and Sergio Brutti et al, A new Sn – C / LiFe0.1Co0.9PO4 full lithium - ion cell with ionic liquid - based electrolyte, Materials Letters, 2015, 139, 329 - 332.
[27] Stefan Michael Rommel and Jan Rothballer et al, Characterization of the carbon - coated LiNi1-yCoyPO4 solid solution synthesized by a non - aqueous sol - gel route, Ionics, 2015, 21: 325 - 333.
[28] Dong - Wook Han and Yong - mook kang et al, Effects of Fe doping on the electrochemical performance of LiCoPO4 / C composites for high power - density cathode materials, Electrochemistry Communications, 2009, 11, 137 - 140.
[29] Fei Wang and Jun Yang et al, Highly promoted electrochemical performance of 5 V LiCoPO4 cathode material by addition of vanadium, Journal of Power Sources, 2010, 195, 6884 - 6887.
[30] Huanhuan Li and Yaping wang et al, Improved electrochemical performance of 5 V LiCoPO4 cathode materials via yttrium doping, Solid State Ionics, 2014, 255, 84 - 88.
[31] Vijay Singh and Yelena Gershinsky et al, Magnetism in olivine - type LiCo1-xFexPO4 cathode materials: bridging theory and experiment, Phys. Chem. Chem. Phys., 2015, 17, 31202 - 31215.
[32] A. Rajalakshmi and V. D. Nithya et al, Physicochemical properties of V5+ doped LiCoPO4 as cathode materials for Li - ion batteries, J Sol - Gel Sci Technol, 2013, 65: 399 - 410.
[33] Lucangelo Dimesso and Christina Spanheimer et al, Properties of Ca - containing LiCoPO4 - graphitic carbon foam composites, Ionics, 2015, 21: 2101 - 2107.
[34] S. M. G. Yang and V. Aravindan et al, Realizing the Performance of LiCoPO4 Cathodes by Fe Substitution with Off - Stoichiometry, Journal of The Electrochemical Society, 2012, 159 ( 7 ) , A 1013 - A 1018.
[35] S. Karthickprabhu and G. Hirankumar et al, Structural and electrical studies on Zn2+ doped LiCoPO4, Journal of Electrostatics, 2014, 72, 181 - 186.
[36] Yong - Mook Kang and Yong - Il Kim et al, Structurally stabilized olivine lithium phosphate cathodes with enhanced electrochemical Properties through Fe doping, Energy & Environmental Science, 2011, 4, 4978 - 4983.
[37] Huanhuan Li and Yunxing Li et al, Microwave assisted synthesis of core - shell LiFe1/3Mn1/3Co1/3PO4 / C nanocomposite cathode for high - performance lithium - ion batteries, Journal of Alloys and Compounds, 2014, 617, 154 - 159.
[38] A. Vadivel Murugan and T. Muraliganth et al, Dimensionally Modulated, Single - Crystalline LiMPO4 ( M = Mn, Fe, Co, and Ni ) with Nano - Thumblike Shapes for High - Power Energy Storage, Inorganic Chemistry, 2009, Vol. 48, No. 3, 946 - 952.
[39] Angelina Sarapulova and Daria Mikhailova et al, Disordered carbon nanofibers / LiCoPO4 composites as cathode materials for lithium ion batteries, J Sol - Gel Sci Technol, 2012, 62: 98 - 110.
[40] Qian Sun and Jia - Yan Luo et al, Facile Synthesis and Electrochemical Properties of Carbon - Coated LiCoPO4 Submicron Particles as Positive Materials for Lithium Ion Batteries, Electrochemical and Solid - State Letters, 2011, 14 ( 10 ) , A 151 - A 153.
[41] Jiangfeng Ni and Yuhai Han et al, One - pot synthesis of CNT - wired LiCo0.5Mn0.5PO4 nanocomposites, Electrochemistry Communications, 2013, 31, 84 - 87.
[42] P. N. Poovizhi and S. Selladurai, Study of pristine and carbon - coated LiCoPO4 olivine material synthesized by modified sol - gel method, Ionics, 2011, 17: 13 - 19.
[43] M. K. Devaraju and Q. D. Truong et al, Supercritical fluid methods for synthesizing cathode materials towards lithium ion nattery applications, RSC Advances, 2014, 4, 27452 - 27470.