摘要
微孔型聚合物电解质膜具有较高的室温电导率和较好的热力学稳定性,同时可降低组装电池过程中对环境干燥程度的要求,是最有希望应用于锂离子电池的一类聚合物电解质膜。然而,传统的研究方法仍无法解决聚合物膜电导率同机械强度之间的矛盾。为了解决这一问题,我们对无机粒子添加的复合微孔型聚合物电解质膜进行了研究。
本文通过分子筛添加的方法对锂离子电池用聚合物电解质膜进行了改性。首先根据溶胶-凝胶原理,实验室合成了介孔分子筛MCM-41,并对其进行了表面酸化改性,在分子筛上负载了固体超强酸SO42-/ZrO2,制备出改性介孔分子筛MCM-41-SZ粒子。而后,本论文采用相转化法,以聚偏氟乙烯(PVDF)为聚合物基体,丙酮为溶剂,将改性介孔分子筛添加到聚合物中制备了一种新型的锂离子电池聚合物电解质膜MCM-41-SZ/PVDF。实验对相转移法制备聚合物电解质膜的相关工艺进行了优化,确定采用干法相转化法制膜,固液比为1:8,分子筛添加量为10%(wt.%PVDF)时,制备的聚合物膜性能最佳。
聚合物电解质膜的性能测试显示聚合物电解质膜的性能得到了提高:聚合物膜的厚度在40μm左右;孔隙率可达62%;机械拉伸强度可达7.8MPa;吸液率可达161%。
聚合物电解质膜组装成样品锂离子电池后,电池的电化学性能测试结果显示:电池的首次充放电效率可达92%,电池循环20次后,其充放电循环效率仍高达99.9%;电池循环20次后,其容量仍占电池初始容量的90%;电池电压充放电平台较平稳,保持在3.8V左右;聚合物电解质膜的本体电阻较小,为5.95ohm,聚合物电解质膜的离子电导率能够达到0.71×10-3 S/cm。
与空白聚合物电解质膜相比,我们所制备的MCM-41-SZ/PVDF聚合物电解质膜的孔隙率、机械拉伸强度和膜的离子电导率都较高,组装成的样品锂离子电池充放电性能稳定,符合商品化锂离子电池的要求。
Micro-porous polymer electrolyte membranes have wide application prospect in lithium-ion batteries, due to their high conductivity at room temperature, excellent thermodynamic stability and low requirement of environment dryness. However, it is difficult to obtain membranes which have both good conductivity and excellent mechanical property. In order to solve this problem, inorganic particles can be doped into micro-porous polymer electrolyte membranes.
In this paper, micro-porous polymer electrolyte membranes were modified by adding inorganic particles (molecular sieves). First, modified mesopore molecular sieves (MCM-41-SZ) were synthesized by loading solid super acid SO42-/ZrO2 on MCM-41. Then novel MCM-41-SZ/PVDF polymer electrolyte membranes were prepared by doping MCM-41-SZ into PVDF via phase inversion method. The optimal preparation conditions of the polymer electrolyte membranes are: dry phase inversion method; solid-liquid molar ratio, 1:8; mass ratio of MCM-41-SZ to PVDF, 10%.
Measurements of the polymer electrolyte membranes show that porosity, tensile strength and liquid absorption rate of membranes have been improved. Results were listed as follows: thickness of the membrane is about 40μm, porosity 62%, tensile strength 7.8MPa and liquid absorption rate 161%, which can fit the requirement of commercial lithium-ion batteries.
The electrochemical characteristics of lithium-ion batteries assembled by using polymer electrolyte membranes show that: first discharge-charge efficiency of the battery is 92%, discharge-charge efficiency of the battery 99.9% after twenty cycles, capacity of the battery 90% of initial capacity after twenty cycles, discharge-charge voltage plat of the battery 3.8V, impedance of the polymer electrolyte membrane about 5.95ohm and the corresponding conductivity 0.71×10-3 S/cm.
Compared with PVDF membranes, the MCM-41-SZ/PVDF polymer electrolyte membranes have higher porosity, stronger tensile strength, higher ion conductivity and steady electrochemical properties after assembling into lithium-ion batteries, which fit the requirement of commercial lithium-ion batteries.
引文
[1] Kasavajjula U, Wang C S, Appleby A J, Nano and bulk silica on-based insertion anodes for lithium-ion secondary cells, J. Power Source, 2007, 163(2): 1003～1039
[2] Aurbach D, Markovsky B, Salitra G et al, Review on electrode-electrolyte solution interactions related to cathode materials for Li-ion batteries, J. Power Source, 2007, 165 (2): 491～499
[3] Zhang S S, A review on electrolyte additives for lithium-ion batteries, J. Power Source, 2006, 162(2): 1379～1394
[4]吴宇平,万春荣,姜长印等,锂离子电池,北京:化学工业出版社,2002,13～16
[5]吴宇平,戴晓兵,马军旗等,锂离子电池—应用与实践,北京:化学工业出版社,2004,306～308
[6] Nagaura T, Proceedings of the 5th International Seminar on Lithium Battery Technology and Applications, Florida USA, Deerfield Beach., 1990, 5～8
[7]郭炳焜,徐徽,王先友等,锂离子电池,长沙:中南大学出版社,2003,291～314
[8]吴宇平,张汉平,吴锋等,绿色电源材料,北京:化学工业出版社,2008,10～11
[9]吴宇平,张汉平,吴锋等,聚合物锂离子电池,北京:化学工业出版社,2006,2
[10] Gozdz A S, Scumutz C N, Tarascon J M, Rechargeable lithium intercalation battery with hybrid polymeric electrolyte, US Pat, NO 5296318, 1993-03-5
[11]邓正华,李仁贵,王璐等,隔膜的孔结构、理化特性与锂离子电池性能的相关性,新材料产业,2007,8:56～59
[12]陈白珍,袁艳,PVDF-HFP聚合物微孔膜的制备及其在锂离子电池中的应用,硕士论文,中南大学,2007
[13] Song J Y, Wang Y Y, Review of gel-type polymer electrolytes for lithium-ion batteries, J. Power Source, 1999, 77(1): 183～197
[14] Wright P V, Electrical conductivity in ionic complexes of poly(ethylene oxide), Br. Polym. J., 1975, 7: 319～327
[15] Armand M B, Chabagno J M, Duclot M, Second International Meeting on Solid Electrolytes, Scotland, St. Andrews, 1978, Sept: 20～26
[16] Kim S H, Kim J Y, Solid State Ionics, Ionic conductivity of polymer electrolytes based on phosphate and polyether copolymers, 1999, 116(1-2): 63～71
[17] Fujinami T, Mehta M A, Sugie K, et al, Molecular design of inorganic–organic hybrid polyelectrolytes to enhance lithium ion conductivity, Electrochimica Acta, 2000, 45(8-9): 1181～1186
[18]席靖宇,马晓梅,崔孟忠等,PEO-LiClO4-ZSM5复合聚合物电解质的电化学研究,科学通报,2004,49(3):217～220
[19] Song Y X, Wu S Y, Jing X B, et al, Thermal, mechanical and ionic conductive behaviour of gamma-radiation induced PEO/PVDF(SIN)-LiClO4 polymer electrolyte system, Radiation Phys. Chem., 1997, 49(5): 541～546
[20] Lee K H, Lee Y G, Park J K et al, Effect of silica on the electrochemical characteristics of the plasticized polymer electrolytes based on the P(AN-co-MMA)copolymer, Solid State Ionics, 2000, 133(3-4): 257～263
[21]唐定国,刘建红,慈云祥等,一种新型凝胶态聚合物电解质的制备和性能,物理化学学报,2005,21(11):1263～1268
[22] Subramania A, Kalyana NT, Sundaram et al, Development of PVA based micro-porous polymer electrolyte by a novel preferential polymer dissolution process, J. Power Sources, 2005, 141(1): 188～192
[23] Kim S H, Choi J K, Bae Y C, Mechanical properties and ionic conductivity of gel polymer electrolyte based on PVDF-HFP, J. Appl. Sci., 200l, 81(2): 948～956
[24] Boudin F, Andrieu X, Jehoulet C et al, Microporous PVDF gel for lithium-ion Batteries, J. Power Sources, 1999, 81-82(9): 804～807
[25]汪国杰,潘慧铭,干/湿相转化法制备偏氟乙烯-六氟丙烯共聚物对称微孔膜,膜科学与技术,2001,21(6):5～10
[26]孙志能,付红平,洪若瑜,纳米二氧化硅填充PVDF聚合物电解质微孔膜的研究,精细化工,2008,25(2):109～113
[27] Best A S, Ferry A, Macfarlane D R et al, Conductivity in amorphous polyether nano composite materials, Solid State Ionics, 1999, 126(3-4): 269～276
[28] Wang C E, Wei Y, Ferment G R et al, Poly(ethylene oxide)-silica hybrid materials for lithium battery application, Mater. Lett., 1999, 39: 206～210
[29] Rajendran S, Uma T, Effect of ceramic oxide on PMMA based polymer electrolyte systems, Mater. Lett., 2000,45(3-4): 191～196
[30] Ardel G, Golodnisky D, Peled E, Grain boundary phenomena in LiI-PEO-Al2O3-based composite solid electrolytes; Holmes C F, Landgrebe A R, Proceeding of the symposium on batteries for portable applications and electric vehicles, Electrochem. Soc., INC, 1997, 97(18): 272～280
[31] Rajendran S, Uma T, Effect of ZrO2 on conductivity of PVC-LiBF4-DBP polymer electrolytes, Mater. Lett., 2000, 44(3-4): 208～214
[32] Bai Y, Wu C, Wu F, Microstructure and electrochemical performances of LiF-coated spinel LiMn2O4, Transactions of nonferrous Matals Society of China, 2007, 17(3): S892～S896
[33] Sundaram NTK, Subramania A, Microstructure of PVdF-co-HFP based electrolyte prepared by preferential polymer dissolution process, J. Power Source, 2007, 289 (1-2): 1～6
[34] Sudou Y, Suzuki H, Nagami HS et al, Separator for battery and lithium ion battery using the same, US Pat. 20060073389
[35] Kim J R, Choi S W, Jo S M et al, Characterization and Properties of P(VdF-HFP)-Based Fibrous Polymer Electrolyte Membrane Prepared by Electrospinning, J. Power Source, 2005, 152(2): A295～A300
[36] Zhang S S, A review on the separators of liquid electrolyte Li-ion batteries, J. Power Source, 2007, 164 (1): 351～364
[37] Merke T C, Freeman B D, Spontak R, J et al, Ultrapermeable, Reverse-Selective Nanocomposite Membranes, Science, 2002, 296(19): 519～522
[38] Capadona J R, Van Den Berg O, Capadona L A, et al, A versatile approach for the processing of polymer nanocomposites with self-assembled nanofibre templates, Nature Nanotechnology, 2007, 2(12): 765～769
[39] Kulkarni S S, Tambe S M, Kittur A A, et al, Preparation of novel composite membranes for the pervaporation separation of water-acetic acid mixtures . J. Power Source, 2006, 285(1-2): 420～431
[40] Gomes D, Nunes S P, Peinemann K V, Membranes for gas separation based on poly(1-trimethylsilyl-1-propyne)-silica nanocomposites, J. Membr. Sci., 2005, 246(1): 13～25
[41]张裕卿,丁健,Al2O3的添加对聚砜膜性能的影响,化学工程,2000,171(5):42～44
[42] Subramania A, Sundaram NTK, Priya ARS et al, Preparation of a novel composite micro-porous polymer electrolyte membrane for high performance Li-ion battery, J. Membr. Sci., 2007, 294(1-2): 8～15
[43]冯华君,陈渊,代克化等,一种新型锂离子电池用聚合物电解质复合膜的制备和性能表征,物理化学学报,2007,23(12):1922～1926
[44]李朝晖,苏光耀,王霞瑜等,纳米A12O3填充PVDF-HFP复合电解质的导电性,高等学校化学学报,2003,24(11):2065～2068
[45]李立,苑克国,张育川等,二次锂电池用PVDF-HFP/SiO2复合聚合物隔膜的研究,北京化工大学学报,2006,33(2):55～58
[46] Jiang Y X, Chen Z F, Zhuang Q C et al, A novel composite microporous polymer electrolyte prepared with molecule sieves for Li-ion batteries, J. Power Sources, 2006, 160(2): 1320～1328
[47] Kim K M, Kim J C, Ryu K S, Characteristics of PVDF-HFP/TiO2 Composite Electrolytes Prepared by a Phase Inversion Technique Using Dimethyl Acetamide Solvent and Water Non-Solvent, Macromol. Mater. Eng., 2006, 291: 1495～1501
[48] Vijayakumar G., Karthick S N, Sathiya Priya A R et al, Effect of nanoscale CeO2 on PVDF-HFP-based nanocomposite porous polymer electrolytes for Li-ion batteries, J. Solid State Electrochem, 2008, 12: 1135～1141
[49] Tang D G, Liu J H, Qi L et al, Composite polymer electrolyte membranes supported by non-woven fabrics for lithium-ion polymer batteries, Chinese Science Bulletin, 2005, 50(6): 501～504
[50]席靖宇,黄小彬,唐小真,固体超强酸为填料的纳米复合聚合物电解质,第十二届中国固态离子学学术会议论文,2004,F44:548～550
[51] Tsujimoto Y, Tassel C, Hayashi N et al, Infinite-layer iron oxide with a square-planar coordination, Nature, 2007, 450(13): 1062～1066
[52] Zhang Y Q, Qin Z, Tu Z Y, Study of the preparation of flavone imprinted silica microspheres and their molecular recognition function, Chem. Eng. Techno., 2007, 30(8): 1014～1019
[53] Zhang Y Q, Zhang Y H, Zhang H L, Study on preparation of a novel silica adsorbent and its selective separation for genistein, Brazilian J. Chem. Eng., 2008, 25(1): 201～206
[54] Petit L, Griffin J, Carlie N, Luminescence Properties of Eu3+orDy3+/Au Co-doped SiO2 Nanoparticles, Mater. Lett., 2007, 61(14-15): 2879～2882
[55] Avrami M, Kinetics of phase changeII. Transformation-time relation for random distribution of nuclei, J. Chem. Phys., 1992, 8: 212～224
[56] Avrami M, Kinetics of phase changeIII granulation, phase change and microstructure, J. Chem. Phys., 1994, 9: 177～178
[57] Monnier A, Schuth F, Huo Q S et al, Cooperative Formation of Inorganic-organic Interface in the Synthesis of Silicate Mesostructures, Science, 1993, 14(13): 1299～1302
[58] Kresge C T, Leonowicz M E, Roth W J et al, Ordered mesoprosous molecular sieves synthesized by a liquid-crystal template mechanism, Nature, 1992, 359: 710～712
[59]陈作锋,姜艳霞,庄全超等,一种新型微孔聚合物电解质的制备与表征,科学通报,2005,50(7):638～642
[60] Xi J Y, Qin X P, Chen L Q, PVDF–PEO/ZSM-5 based composite microporous polymer electrolyte with novel pore configuration and ionic conductivity, Solid State Ionics, 2006, 177(7-8): 709～713
[61] Chu P P, Reddy M J, Kao H M, Novel composite polymer electrolyte comprising mesoporous structured SiO2 and PEO/Li, Solid State Ionics, 2003, 156(1-2): 141~153
[62]陈作锋,姜艳霞,庄全超等,MCM-41介孔分子筛掺杂的微孔型聚合物电解质的制备与表征,电化学,2005,11(2):162～166
[63]张裕卿,张红柳,曲云,填充纳米SiO2对聚偏氟乙烯膜性能的影响,膜科学与技术,2007,27(6):47～51
[64]张裕卿,陈超,朱勇军等,具有中间相结构的纳米Al2O3?SiO2-聚砜复合膜的制备方法,中国发明专利,ZL03130377.3
[65]张裕卿,李海平,吴三械等,几种添加剂对铅酸蓄电池低温充放电性能的影响,电源技术,1997,21(2):53～56
[66]徐如人,庞文琴等,分子筛与多孔材料化学,北京:科学出版社,2004,528～615
[67]金日光,华幼卿,高分子物理,北京:化学工业出版社,2006,235～236
[68]白莹,吴川,吴锋等,纳米SiO2对聚合物隔膜的影响,电池,2006,36(3):165～167