水热法制备锂离子电池正极材料LiFePO_4
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摘要
本文采用一步沉淀和两步沉淀法制备水热反应前驱体,在不同的条件下对前驱体进行水热处理,合成了LiFePO_4粉体,并对LiFePO_4进行掺杂改性。探讨水热法制备LiFePO_4的工艺原理、水热法工艺参数和掺杂改性对LiFePO_4结构、微观形貌、电化学性能以及振实密度的影响。
     研究一步沉淀和两步沉淀两种工艺制备水热反应前驱体的机理,前驱体沉淀中Li与Fe元素的含量的测试表明,两种前驱体沉淀中都含有Li与Fe元素,但溶液中Li与Fe元素并未按化学计量比完全转化为沉淀,同时XRD分析表明前驱体为非晶态,因此水热反应过程是前驱体的进一步沉淀、LiFePO_4的结晶和晶体的长大过程。
     对一步沉淀和两步沉淀两种前驱体制备工艺制备的前驱体进行水热处理,分析前驱体制备工艺、水热时间和水热反应温度对最终产物充放电性能的影响。通过样品的充放电测试结果表明最佳水热反应条件为:一步沉淀的前驱体工艺中,反应温度150℃,反应时间1 h。两步沉淀的前驱体工艺中,反应温度为190℃,反应时间1 h。粉体的比表面积测试表明随着粉体合成温度的提高,粉体的比表面积逐渐减小,比表面积较小的平台电压较好。
     研究水热反应条件对振实密度的影响。通过研究发现,反应时间延长,振实密度随之降低;水热反应温度升高,相应的振实密度降低;粉体的吸潮使得粉体的流动性变差,在过80目筛的振实密度测试中发现吸潮测得振实密度很低,而过300目筛测试结果吸潮影响较小,实验中大部分粉体的振实密度在1~1.5 g·cm~(-3),这与商业化产品的振实密度指标相近。
     对LiFePO_4正极材料进行掺杂改性研究,探讨掺杂Mg对正极材料的充放电性能和振实密度的影响。通过研究发现,掺杂5mol.%Mg使得正极材料结晶良好,形貌均一,颗粒的粒径也有所减小,并且正极材料具有明显的充放电平台,较之未掺杂的样品充放电比容量也有很大提高,这说明掺杂5mol.%Mg有效的提高了正极材料的充放电性能;掺杂5mol.%Mg样品的正极材料振实密度较之未掺杂样品有所下降。
LiFePO_4 cathode materials were prepared by hydrothermal reaction method with precursors at different conditions. The precursors were synthesized by precipitation named one step and two steps separately. The study on doping modification of LiFePO_4 was carried out. The principle of hydrothermal reaction synthesizing LiFePO_4 was investigated. At the same time, influences of the technology parameters and doping modification on structure, morphology, electrochemical properties and tap density of the cathode materials were discussed.
     The mechanism of precursors prepared by precipitation of one step and two steps separately was investigated. The results indicate that there were Li and Fe in the precursors. However, the Li and Fe in the solution didn’t transfer to precipitation by stoichiometric ratio. X-ray diffraction analysis of the precursors suggests that the precursor is amorphous. Therefore it was a further precipitation of precursors, a crystallization and growth of LiFePO_4 during the hydrothermal reaction.
     The precursors were crystallized by hydrothermal reaction. Influences of the process of synthesizing the precursor, time and temperature of hydrothermal reaction on tap density, charging and discharging properties of the cathode materials were discussed. The optimized conditions of hydrothermal reaction were obtained. One is the sample with reaction temperature 150°C and reaction time 1h in precipitation of one step, the other is the sample with reaction temperature 190°C and reaction time 1h in precipitation of two steps. The special surface area of powders analysis indicates that the special surface area decrease gradually by the increasing of temperature, and the smaller one exhibit better flat voltage.
     The tap density of cathode powder was tested. The results suggest that, the tap density is gradually decreased by increasing reaction time and enhancing the reaction temperature. The fluidity of the cathode powder deteriorated because of the powder absorbing dampness. The tap density of the sample obtained with a 300 mesh sieve is very low. However, influence of the powder absorbing dampness on tap density of the sample obtained with a 300 mesh sieve is sensitive. Most of the cathode tap density is between 1 g·cm~(-1) and 1.5 g·cm~(-1). The results of tap density are close to the tap density of commercial products.
     The doping modification of LiFePO_4 was studied, the effects of Mg doping on the tap density, charging and discharging properties of the LiFePO_4 cathode material were discussed. The results reveal that, the doping of 5 mol. % Mg is benefit for the growth of the crystal grain by XRD and SEM, the grain size is decreased, there are charge and discharge flats of cathode material obviously, the specific capacity of the doping of 5 mol. % Mg are increased than the no doping one, however the tap density of the doping of 5 mol. % Mg is more decreased than the no doping one.
引文
[1]顾健,顾大明,史鹏飞.锂离子电池正极材料LiNi0.8Co0.2O2的研究[J].精细化工,2004,21(2):88.
    [2]吴宇平,戴晓兵,马军旗等.锂离子电池-应用与实践[M].北京:化学工业出版社,2004,4-5.
    [3]苏金然,秦兴才,贾宏涛.锂离子电池的发展动态[J].中国电子商情,2006,10:40-43.
    [4] Schalkwijk W A, Scrosati B. Advances in Lithium-Ion Batteries. New York: Kluwer Academic, 2002.
    [5] T. Ohzuku, Y. Iwakoshi, K. Sawai. Formation of lithium-grap Hite intercalation compounds in nonaqueous electrolytes and their application as a negative electrode for a lithium ion (Shuttlecock) cell[J]. Electrochemical Society, 1993, 140: 2490-2495.
    [6] R. Fong, U. V. Sacken, J. R. Dahn. Studies of lithium intercalation into carbon using nonaqueous electrochemical cells[J]. Electrochemical Society, 1990, 137: 2009-2013.
    [7] Gabrielle Nadeau, Xiang Yun Song, Monique Massé, et al. Effect of heat treatment and additives on the particles and carbon fibers as anodes for lithium-ion batteries[J]. Journal of Power Sources, 2002, 108: 86-96.
    [8] J. M. Skowro ski, K. Knofczy ski, Y. Yamada. Mechanism of lithium insertion in hollow carbon fibers-based anode[J]. Solid State Ionics, 2003, 157 (1-4): 133-138.
    [9] Kazuhisa Naga, Tsuyoshi Nakajima, Shinya Aimura, et al. Electrochemical behavior of surface-modified petroleum cokes in propylene carbonate containing solvents[J]. Journal of Power Sources, 2007, 167(1): 192-199.
    [10] M.Jean, A.Chausse, R.Messina. Studies of petroleum coke in carbonate-based electrolyte[J]. Journal of Power Sources, 1997, 68(2): 232-235.
    [11] T. D. Tran, L. M. Spellman, W. M. Goldberger, et al. Lithium intercalation in heat-treated petroleum cokes[J]. Journal of Power Sources, 1997, 68(1): 106-109.
    [12]唐致远,庄新国,翟玉梅.锂离子电池负极材料研究进展[J].电源技术,2002,32:108-111.
    [13]江志裕.锂离子电池的某些研究发展[J].电池,1997,6:255-259.
    [14] Liwei Zhao, Izumi Watanabe, Takayuki Doi, et al. TG-MS analysis of solidelectrolyte interphase (SEI) on graphite negative-electrode in lithium-ion batteries[J]. Journal of Power Sources, 2006, 161(2): 1275-1280.
    [15] K. Mizushima, P. J. Wiseman, J. B. Goodenough, et al. Li_xCoO_2 (0    [16]郭炳焜,徐徽,王先友等.锂离子电池[M],长沙:中南大学出版社.2002,93-94.
    [17]吴宇平,万春荣,姜长印.锂离子二次电池[M].北京:化学工业出版社,2002.
    [18]唐致远,李建刚,薛建军等.锂离子电池正极材料LiMnO2的改性与循环寿命[J].化学通报,2000,8:10-14.
    [19]黄原君,苏光耀,雷钢铁等.多元复合正极材料LiCo1/3Mn1/3Ni1/3O2的研究进展[J].材料导报,2006,20:285-287.
    [20] Padhi A K, Nanjundaswamy K. S, Goodenough J. B. Phospho-olivines as positive electrode materials for rechargeable lithium batteries [J]. Journal Electrochemistry Society, 1997, 144(4): 1188-1194.
    [21] J.-M. Tarascon, M. Armand. Issues and challenges facing rechargeable lithium batteries[J]. Nature, 2001, 414: 359-367.
    [22] Seung-Taek Myung, Shinichi Komaba, Norimitsu Hirosaki, et al. Emulsion drying synthesis of olivine LiFePO4/C composite and its electrochemical properties as lithium intercalation material[J]. Electrochimica Acta, 2004, 49(24): 4213-4222.
    [23] A. S. Andersson, J. O. Thomas. The source of first-cycle capacity loss in LiFePO4[J]. Journal of power sources, 2001, 97-98: 498-502.
    [24] Morgan D, et al. Li conductivity in LixMPO4 (M=Mn, Fe, Co, Ni) olivine materials[J]. Electrochemistry Solid-State Letter, 2004, 7(2): A30.
    [25]郭炳焜,徐徽,王先友等.锂离子电池[M],长沙:中南大学出版社.2002,93-94.
    [26] Fernanda F. C. Bazito, Roberto M. Torresi. Cathodes for Lithium Ion Batteries: The Benefits of Using Nanostructure Materials[J]. Journal of the Brazilian Chemical Society, 2006, 17(4): 627-642.
    [27] Per Andersson, Stina Alm, Kjell Edman, et al. Lithium extraction/insertion in LiFePO4 : an X-ray diffraction and M?ssbauer spectroscopy study [J]. Solid State Ionics, 2000, 130(1-2): 41-52.
    [28] Padhi A K, Nanjundaswamy K. S, Goodenough J. B. Phospho-olivines as positive electrode materials for rechargeable lithium batteries[J]. Journal of Electrochemical Society, 1997, 144(4): 1188-1194.
    [29] Pier Paolo Prosini, Maria Carewska, Silvera Scaccia, et al. A New SyntheticRoute for Preparing LiFePO4 with Enhanced Electrochemical Performance [J] Journal of the Electrochemical Society, 2002, 149(7): A886-A890.
    [30] A. Yamada, S. C. Chung, K. Hinokuma.Optimized LiFePO4 for Lithium Battery Cathodes[J]. Journal of the Electrochemical Society, 2001, 148(3): A224-A172.
    [31] H. Huang, S. C. Yin, and L. F. Nazar. Approaching Theoretical Capacity of LiFePO4 at Room Temperature at High Rates[J]. Electrochemical and Solid State Letters, 2001, 4(10): A170-A172.
    [32] Takahashi M , Tobishima S , Takei K, et al. Characterization of LiFePO4 as the cathode material for rechargeable lithium batteries [J]. Journal of Power Sources, 2001, 97- 98: 508-501.
    [33] Ravet N, Chouinard Y, Magnan J F, et al. Electro-activity of natural and synthetic triphylite[J]. Journal of Power Sources, 2001, 97-98: 503-507.
    [34] G. Amold, J. Garche, R. Hemmer, et al. Fine particle lithium iron phosphate LiFePO4 synthesized by a new low-cost aqueous precipitation technique[J]. Journal of Power Sources, 2003, 119-121: 247-251.
    [35] Croce F, Epifanio A D, Hassoun J, et al. A novel concept for the synthesis of an improved LiFePO4 lithium battery cathode[J]. Electrochemistry and Solid State Letters, 2002, 5(3): A47-A50.
    [36] Barker J, Saidi M Swoyer J L. Lithium-containing materials: US, 6716372[P]. 2001-10-19.
    [37] Barker J, Saidi M Swoyer J L. Lithium-based active materials and preparation thereof: US, 6723470[P]. 2001-07-18.
    [38] Barker J, Saidi M Swoyer J L, et a1. Methods of making transition metal compounds useful as cathode active materials: US, 6730281[P]. 2002-05-17.
    [39] Barker J, Saidi M Swoyer J L. Alkali transition metal phosphates and related electrode active materials: US, 6815122[P]. 2002-03-06.
    [40]庞文琴.无机合成[M].北京:高等教育出版社,1991.
    [41]高道江,肖定全,张文等,水热电化学技术及其在陶瓷薄膜制备中的应用[J],功能材料,2002,33(3):240-242.
    [42]施尔畏,夏长泰,王步国等,水热发的应用与发展[J],无机材料学报,1996,11(2):193-206.
    [43] Sung-Yoon Chung, Jason T. Bloking, Yet-Ming Chiang. Electronically conductive phospho-olivines as lithium storage electrodes[J]. Nature, 2002, 1: 123-128.
    [44] A. S. Andersson, J. O. Thomas. The source of first-cycle capacity loss in LiFePO4[J]. Journal of power sources, 2000, 97-98: 498-502.
    [45] Shigehisa Tajimi, Yosuke Ikeda, Kazuyoshi Uematsu, et al. Enhancedelectrochemical performance of LiFePO4 prepared by hydrothermal reaction[J]. Solid State Ionics, 2004, 175(1-4): 287-290.
    [46]庄大高,赵新兵,曹高劭等,水热法合成LiFePO4的形貌和反应机理[J],中国有色金属学报,2005,15(12):2034-2039.
    [47] Hee-Cheol Kang, Dae-Kyoo Jun, Bo Jin, et al. Optimized solid-state synthesis of LiFePO4 cathode materials using ball-milling[J]. Journal of power sources, 2008, 179(1): 340-346.
    [48] Shoufeng Yang, Peter Y. Zavalij, M. Stanley Whittingham. Hydrothermal synthesis of lithium iron phosphates cathodes[J], Electrochemistry communications, 2001, 3(9): 505-508.
    [49] G. Meligrana, C. Gerbaldi, A. Tuelb, S. Bodoardo, N. Penazzi, Hydrothermal synthesis of high surface LiFePO4 powders as cathode for Li-ion cells[J], Journal of Power sources, 2006, 160(1): 516-521.
    [50] Kaoru Dokko, Shohei Koizumi, Keisuke Sharaishi, et al, Electrochemical properties of LiFePO4 prepared via hydrothermal route[J], Journal of power sources, 2007, 165(2): 656-659.
    [51] Jaewon Lee, Amyn S. teja. Characteristics of lithium iron phosphate (LiFePO4) particles synthesized in subcritical and supercritical water[J], Supercritical Fluids, 2005, 35(1): 83-90.
    [52]张静,黄可龙,唐联兴.LiFePO4的水热法制备及改性研究[J],电池,2005,35(6):425-426.
    [53] Xiu Qin Ou, Guang Chuan Liang, Jin Sheng Liang, LiFePO4 doped with magnesium prepared by hydrothermal reaction in glucose solution[J], Chinese Chemical Letters, 2008, 19(3): 345-349.
    [54]庄大高,赵新兵,谢健等,碳包覆镍掺杂LiFePO4正极材料的合成与电化学性能[J],稀有金属材料与工程,2007,36(1):149-152.

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