摘要
锂离子电池具有质量轻、比能量高、寿命长及无记忆效应等优点,不仅在民用领域的应用发展迅速,而且在军用通信、航天等高科技领域也有很广的应用前景。由于其特殊使用环境,这些领域对锂离子电池的性能提出了更高的要求。目前限制锂离子电池使用主要因素之一是锂离子电池的低温性能比较差,石墨负极在低温下嵌锂过程极为困难。造成这一现象的主要原因是在低温下石墨负极中锂离子扩散速率小、嵌锂过程中电极/电解液界面上的电荷传递阻抗较大。因此本论文从这两个限制因素入手,分别采用膨胀化处理和氧化处理两种手段对中间相碳微球(mesophase carbon microbeads, MCMB)进行改性,并通过扫描电镜、X射线衍射、电化学交流阻抗等表征手段考察改性后MCMB表面形貌、结构、嵌锂过程阻抗的变化情况,借此探讨了负极低温性能改善的原因。
膨胀化处理MCMB主要目的是增大MCMB石墨层间距,提高锂离子在MCMB中的迁移能力。结果发现,随着膨胀化程度的增加,MCMB的低温性能得到明显改善。阻抗结果分析发现膨胀化中间相碳微球锂离子扩散系数比未经处理的中间相碳微球高三个数量级,达到1.36×10-10cm2s-1,-40℃循环容量可达到38mAh.g-1,经过热处理,-40℃循环容量可进一步达到101mAh.g-1。
氧化处理MCMB目的在于改变石墨表面官能团的种类和数量,进而调控MCMB充放电过程中形成的固体电解质(Solid Electrolyte Interface, SEI)膜的厚度与组成,增加SEI膜电导率。同时,氧化可能会引起表面形貌的变化,形成孔道结构,增大锂离子扩散系数。试验结果发现,氧化后SEI膜阻抗增大,扩散系数增大,表面微观结构基本无变化,对低温容量的提高作用很小。因此单纯表面氧化不能使石墨负极的低温脱嵌锂性能得到提高。
Li-ion battery has the advantages of low equivalent weigh, high theoretical capacity, long cycle life, no memory effection and so on. So it can be applied not only in civilian areas, but also in military communications, aerospace and other high-tech fields, thus the performance of li-ion battery has to fit these fields. One of the main factors restricts the use of li-ion battery is its poor performance at low temperature. The main reasons for this phenomenon are the low lithium ion diffusion rate and large charge transfer resistance. In this work the mesophase carbon microbead (MCMB) was modified to investigate the influences of expanding and oxidation effection on the low temperature performance of li-ion battery. Scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) were used to characterize the surface morphology, structural characteristics and resistance of the modified MCMB.
Expanded MCMB was prepared to increase the li-ion diffusion coefficient. It was found that the low temperature performance of MCMB had been significantly improved with the increase of expansion. The study of EIS found that the li ion diffusion coefficient of expanded MCMB was three orders magnitude higher than that of unmodified. The capacity of expanded MCMB at -40℃could reach to 38mAhg-1. By heat treated, the capacity of expanded MCMB at -40℃could reach to 101mAhg-1.
Oxidate treated MCMB was prepared to change the types and quantities of surface groups, and change the thickness and composition of the solid electrolyte formed on the anode, to increase the conductivity of Solid Electrolyte Interface (SEI). Meanwhile, Oxidation might leads to changes in surface morphology, to form the pore structure and increase the li ion diffusion coefficient. The results showed that after oxidation, the resistance of SEI and the diffusion coefficient increased, but the improvement of low temperature performance was unsatisfied. As a result, just simply surface oxidation treatment couldn’t improve the low temperature performance of graphite anodes.
引文
1王东,李国欣.锂离子电池技术在航天领域的应用.上海航天. 2000, 17(1): 54~58
2 H. Oman. New Battery types for Space Vehicles. Aerospace and Electronic Systems Magazine. 2002, 17(4): 34~40
3 M. C. Smart, R. V. Bugga, L. D. Whitcanack. et al. Life verification of large capacity Yardney Li-ion cells and batteries in support of NASA missions. International Journal of Energy Research. 2010, 34: 116~132
4 M. C. Smart. B. V. Ratnakumar, L. D. Whitcanack. et al. Improved low-temperature performance of lithium-ion cells with quaternary carbonate-based electrolytes. Journal of Power Sources. 2003, 119-121: 349~358
5 J. Fan. On the Discharge Capability and it’s Limiting Factors of Commercial 18650 Li-ion Cell at Low Temperatures. Journal of Power Sources. 2003, 117: 170~178
6 M. C. Smart, B. V. Ratnakumar, S. Surampudi. Electrolytes for Low Temperature Lithium Batteries Based on Ternary Mixture of Aliphatic Carbonates. Journal of Electrochemical Society. 1999, 146: 486~492
7 H. C. Shiao, D. Chua, H. P. Lin. et al. Low Temperature Electrolytes for Li-ion PVDF cell. Journal of Power Sources. 2000, 87: 167~173
8 E. J. Plichta, M. Hendrickson, R. Thompson. et al. Development of Low Temperature Li-ion Electrolytes for NASA and DoD Applications. Journal of Power Sources. 2001, 94: 160~162
9 S. S. Zhang, K. Xu, T. R. Jow. The Low Temperature Performance of Li-ion Batteries. Journal of Power Sources. 2003, 115: 137~140
10 H. P. Lin, D. Chua, H. C. Shiao. et al. Low-Temperature Behavior of Li-ion Cells. Journal of Electrochemical Solid-State Letter. 2001, 4: A71~A73
11 C. K. Huang, J. S. Sakamoto, J. Wolfenstine. et al. The Limits of Low Temperature Performance of Li-ion Cells. Journal of Electrochemical Society. 2000, 147(8): 2893~2896
12 E. J. Plichta, W. K. Behl. A low-temperature electrolyte for lithium and lithium-ion batteries. Journal of Power Sources. 2000, 88: 192~196
13 B. K. Mandal, A. K. Padhi. Z. Shi. et al.New low temperature electrolytes with thermal runaway inhibition for lithium-ion rechargeable batteries. Journal of Power Sources. 2006, 162: 690~695
14 S. herreyre, O. huchet, S. Barusseau. et al. New Li-ion electrolyte for lowtemperature applications. Journal of Power Sources. 2001, 97-98: 576~580
15孔令丽,高俊奎.锂离子电池用低温电解液的研究.电源技术. 2007, 31(9): 747~750
16 S. S. Zhang, K. Xu, J. L. Allen. et al. Effect of Propylene Carbonate on the Low Temperature Performance of Li-ion Cells. Journal of Power Sources. 2002, 110: 216~221
17 S. S. Zhang, K. Xu, T. R. Jow. The Low Temperature Performance of Li-ion Batteries. Journal of Power Sources. 2003, 115: 137~140
18 S. S. Zhang, K. Xu, T. R. Jow. Electrochemical Impedance Study on the Low Temperature of Li-ion Batteries, Electrochimica Acta. 2004, 49: 1057~1061
19 A. N. Jansen, D. W. Dees, D. P. Abraham. et al. Low-Temperature Study of Lithium-ion Cells using a LiySn Micro-reference Electrode. Journal of Power Sources. 2007, 174:373~379
20 K. Tatsumi, J. Conard, M. Nakahara. et al. Low Temperature Li7-NMR Investigations on Lithium Inserted into Carbon Anodes for Rechargeable Lithium-ion Cells. Journal of Power Sources. 1999, 81–82: 397~400
21颜剑,苏玉长,苏继桃等.锂离子电池负极材料的研究进展.电池工业. 2006, 11(4): 277~281
22马荣骏.锂离子电池负极材料的研究及应用进展.有色金属. 2008, 60(2): 38~45
23谭玲生,田爽,郝德利等.锂离子电池在航天电源中应用的研究进展.中国宇航学会空间能源年会. 2002
24 L. J. Fu, H. Liu, C. Li. et al. Surface modifications of electrode materials for lithium ion batteries. Solid State Sciences. 2006, 8: 113~128
25 C. Menachem, Y. Wang, J. Flowers. et al. Characterization of Lithiated Natural Graphite before and after Mildoxidation. Journalof Power Sources. 1998, 76: 180~185.
26 X. Y. Cao, J. H. Kim, S. M. Oh. The Effects of Oxidation on the Surface Properties of MCMB-6-28. Electrochimica Acta. 2002, 47 : 4085~4089
27 Y. P. Wu, C. Jiang, C. Wan. et al. Anode Materials for Lithium Ion Batteries by Oxidative Treatment of Common Natural Graphite. Solid State Ionics. 2003, 156: 283~290
28王红强,李庆余,韦卉等.表面氧化改性中间相炭微球用于锂离子动力电池负极材料的研究.金属材料与冶金工程. 2007, 35(1): 6~9
29 W. Q. Mao, J. M. Wang, Z. H. Xu. et al. Effects of the Oxidation Treatment with K2FeO4 on the Physical Properties and Electrochemical Performance of AnaturalGraphite as Electrode Material for Lithium Ion Batteries. Electrochemistry Communications. 2006, 8: 1326~1330
30 Y. P. Wu, R. Holze. Anode Materials for Lithium Ion Batteries Obtained by Mildand Uniformly Controlled Oxidation of Natural Graphite. Solid State Eletrochem. 2003, 8: 73~78.
31 T. Nakajima. Fluorine-Containing Energy Conversion Materials. Journal of Fluorine Chemistry. 2000, 105: 229~238
32 K. Matsumoto, J. L. Li, Y. Ohzawa. et al. Surface Structure and Electrochemical Characteristics of Natural Graphite Fluorinated by ClF3. Journal of Fluorine Chemistry. 2006, 127: 1383~1389
33 T. Nakajima, H. Groult. Fluorinated Materials for Energy Conversion, Elsevier, Amsterdam, USA, 2005, 31~59.
34 L. J. Fu, H. P. Zhang, Y. P. Wu. et al. Surface Active Sites: An Important Factor Affecting the Sensitivity of Carbon Anode Material toward Humidity. Electrochemical And Solid State Letters. 2005, 9: A456~A458
35周向阳,胡国荣,李庆余等.化学镀银鳞片石墨作锂离子电池负极材料.电池, 2002, 32(5): 255~257
36毛文曲.锂离子二次电池负极材料天然石墨的改性研究.浙江大学硕士论文. 2006: 58
37唐致远,潘丽珠,刘春燕.锂离子电池石墨负极材料表面镍包覆.电池. 2002, 32 (4) : 194~1961
38 J. Gao, H. P. Zhang, T. Zhang. et al. Preparation of Cu Coating on Graphite Electrode Foil and its Suppressive Effect on PC Decomposition. Solid State Ionics. 2007, 178: 1225~1229
39 J. Gao, H. P. Zhang, L. J. Fu. Suppressing Propylene Carbonate Decomposition by Coating Graphite Electrode Foil with Silver. Electrochimica Acta. 2007, 52: 5417-5421
40 L. J. Fu, J. Gao, T. Zhang. et al. Effect of Cu2O Coating on Graphite as Anode Material of Lithium Ion Battery in PC-based Electrolyte. Journal of Power Sources. 2007, 171: 904~907
41 J. Gao, L. J. Fu, H. P. Zhang. et al. Improving Electrochemical Performance of Graphitic Carbon in PC-based Electrolyte by Nano-TiO2 Coating. ElectrochimicaActa. 2008, 53: 2376~2379
42 J. H. Lee, H. Y. Lee, S. M. Oh. et al. Effect of Carbon Coating on Electrochemical Performance of Hard Carbons as Anode Materials for Lithium-ion Batteries. Journal of Power Sources. 2007, 166: 250~254
43 Y. Yang, W. J. Peng, H. J. Guo. et al. Effects of Modification on Performance of Natural Graphite Coated by SiO2 for Anode of Lithium Ion Batteries. Trans. Nonferrous Met. SOC. China. 2007, 17: 1339~1342
44 C. C. Chang. Sb-coated Mesophase Graphite Powder as Anode Material for lithium-ion batteries. Journal of Power Sources. 2008, 175: 874~880
45 Q. M. Pan, H. B. Wang, Y. H. Jiang. Natural Graphite Modified with Nitrophenyl Multilayers as Anode Materialsfor Lithium Ion Batteries. Mater. Chem. 2007, 17: 329~334
46 Q. M. Pan, K. K. Guo, L. Z. Wang. et al. Ionic Conductive Copolymer Encapsulated Graphite as an Anode Material for Lithium Ion Batteries. Solid State Ionics, 2002, 149: 193~200
47 S. S. Zhang, K. Xu, T. R. Jow. Effect of Li2CO3-coating on the Performance of Natural Graphite in Li-ion Battery. Electrochemistry Communications. 2003, 5: 979~982
48 M. Q. Li, M. Z. Qu, X. Y. He. Electrochemical Properties of Li2ZrO3-coated silicon/graphite/carbon Compositeas Anode Material for Lithium Ion Batteries. Journal of Power Sources. 2009, 188: 546~551
49徐国祥,刘春燕,唐致远.掺杂型炭材料在锂离子电池中的应用.新型炭材料. 2001, 16(1): 72~75
50 N. Alexandrov, Y. P. Wu, S. B. Fang. et al. Carbon Anodes for a Lithium Seccondary Battery based on Polyacrylonitrile. Journal of Power Sources, 1998, 75(2): 201~206
51唐致远,吴菲.改性石墨用作锂离子蓄电池负极材料.电源技术. 2006, 130(2): 155~161
52 N. A. Kaskhedikar, V. Federov, A. Simon. Expanded Graphite as Anode for Lithium Ion Battery. Anorg. Allg. Chem. 2008, 2050
53杨树斌.锂离子电池高性能负极材料的结构设计与研究.北京化工大学博士论文. 2008: 48
54 M. Mancini, F. Nobili, S. Dsoke, et al. Lithium Intercalation and Interfacial Kinetics of Composite Anodes Formed by Oxidized Graphite and Copper. Journal of Power Sources. 2009, 190: 141~148
55 H. Y. Wang, T. Umeno, K. Mizumab. et al. Highly Conductive Bridges between Graphite Spheres to Improve the Cycle Performance of a Graphite Anode in Lithium-ion Batteries. Journal of Power Sources. 2008, 175: 886~890
56 F. Nobili, S. Dsoke, T. Mecozzi. Metal-oxidized Graphite Composite Electrodes for Lithium-ion Batteries. Electrochimica Acta. 2005, 51: 536~544
57 N.Takam, A.Satoh, M. Hara. et al. Large Hysteresis During Lithium Insertion into Andextraction from Highcapacity Disordered Carbons. J. Electrochem. Soc. 1995, 142: 371~378
58周向阳.改性天然石墨的嵌/脱锂性能及嵌锂过程动力学的研究.中南大学博士论文. 2002: 113