纯固态聚合物电解质室温电导率太低，不能满足商业化锂离子电池的要求，而传统液态有机电解质在高温下易燃烧，使锂离子电池不安全。凝胶聚合物电解质同时具固体电解质的高温安全性能和传统液态有机电解质的较高的离子电导率和良好的界面稳定性而被广泛研究和应用，但目前应用的凝胶聚合物电解质的离子电导率和界面稳定性还有待改善。 为了提高凝胶聚合物电解质离子电导率和界面稳定性，本论文制备出三类凝胶聚合物电解质：(1) 乳液聚合法合成聚(甲基丙烯酸丁酯-丙烯腈) P(BMA-co-AN)，通过浸泡将此共聚物涂覆在聚烯烃(PE)隔膜上,制备了聚烯烃多孔膜支撑的聚合物电解质膜，然后浸泡在电解液中得到凝胶聚合物电解质；(2)在已经制备的P(BMA-co-AN)基质中添加纳米Al2O3来制备PE支撑P(BMA-co-AN)/Al2O3多孔聚合物电解质，提升已经制备的P(BMA-co-AN)的综合性能；(3) 在已经制备的P(BMA-co-AN)基质，与聚偏氟乙烯(PVDF)共混，得到复合型聚合物(BMA-co-AN)-PVDF电解质。 通过热重分析(TG)及红外光谱(FTIR)等方法研究了聚合物的性质，通过扫描电镜(SEM)、吸液率测量、交流阻抗(EIS)、线性电位扫描和电池充放电实验等方法研究了聚合物膜和聚合物电解质的性质，得到的结论如下: (1) 以不同比例甲基丙烯酸丁酯(BMA) 和丙烯腈(AN)为单体，用乳液聚合法合成P(BMA-co-AN)共聚物，并以此共聚物制备了聚烯烃(PE)多孔膜支撑的凝胶聚合物电解质膜。结果表明：当单体BMA和AN的比例为2：1时，共聚物P(BMA-co-AN)在168℃范围内有很好的热稳定性；PE支撑的聚合物电解质膜有很好的孔状结构，其吸液率达到200%，室温电导率高达1.59×10−3 S.cm−1。得到的PE支撑的聚合物电解质的电化学稳定窗口为4.8V (vs.Li/Li+)，并且以该聚合物电解质制备的聚合物锂离子电池有良好的循环和倍率放电性能。 (2)在P(BMA-co-AN)基质中添加纳米Al2O3来制备PE支撑P(BMA-co-AN)/Al2O3多孔复合聚合物电解质并研究其性质。结果表明：纳米 Al2O3的加入，能改善以PE支撑P(BMA-co-AN)凝胶聚合物为电解质的锂离子电池的性能。相比于没有添加任何纳米Al2O3的聚合物电解质，添加10%纳米Al2O3的聚合物电解质具有更好的性能，其电导率从1.59×10−3 S.cm−1提高到2.37×10−3 S.cm−1，电化学稳定性从4.8V提高到5.2V（vs.Li/Li+）,界面阻抗从110Ω. cm2减少至 74Ω. cm2。 (3) 用制备的P(BMA-co-AN)基质与聚偏氟乙烯(PVDF)复合，得到复合型聚合物电解质薄膜P(BMA-co-AN)-PVDF并研究其性质。结果表明：P(BMA-co-AN)-PVDF聚合物电解质膜比P(BMA-co-AN)基体膜具有更好的性能，电化学稳定性从4.8 V提高到5.4 V (vs.Li/Li+)，界面阻抗从110Ω. cm2减少至 52Ω. cm2,并且以该聚合物电解质制备的聚合物锂离子电池有良好的循环稳定性能。

The conductivity of solide polymer electrolyte at room temperature is too low to meet the requirement of commercial lithium ion battery, while the traditional organic electrolyte was flammable at high temperature and make lithium ion battery unsafe. Gel polymer electrolyte (GPE) is attractive because it combines the advantages of solide polymer electrolyte and troditional organic elelctrolyte. With the aim to develop polymer membrane with high conductivity and good interface stability for lithium ion batteries, three GPEs were prepared in this work: (1) poly(butyl methacrylate-co-acrylonitrile) (P(BMA-co-AN)) was synthesized by emulsion polymerization with butyl methacrylate (BMA) and acrylonitrile(AN) as monomers. With this polymer, polyethylene (PE)-supported polymer membrane and electrolyte were prepared; (2) Nano-Al2O3 was doped in P(BMA-co-AN) and PE-supported P(BMA-co-AN)/nano-Al2O3 GPE was prepared; (3) P(BMA-co-AN) was mixed with poly(vinylidene fluoride) (PVDF) to develop a gel polymer electrolyte matrix, P(BMA-co-AN)/PVDF. The performances of the synthesized polymers and the prepared polymer membranes and electrolytes were studied with FTIR, TG, SEM, CV, EIS, and charge/discharge test. Following results were obtained: (1) Copolymer, P(BMA-co-AN), was synthesized by solution polymerization with different mole ratios of monomers, BMA and AN. PE-supported copolymer and gel polymer electrolyte(GPE) were prepared with this copolymer and their performances were characterized with FTIR, TGA, SEM, and electrochemical methods. It is found that the GPE using the PE-supported copolymer with BMA to AN=2:1(mole) exhibits an ionic conductivity of 1.59×10−3 S.cm−1 at room temperature. The copolymer is stable up to 168 ℃. The PE-supported copolymer shows a cross-linked porous structure and has 200% (wt) of electrolyte uptake. The electrochemical window of the GPE is 4.8V (vs.Li/Li+). With the application of the PE-supported GPE in lithium ion battery, the battery shows its good rate and initial discharge capacity and cyclic stability. (2) Nano-Al2O3 was doped in P(BMA-co-AN) and PE-supported P(BMA-co-AN)/nano-Al2O3 GPE was prepared. The performances of the prepared GPE for lithium ion battery use, including ionic conductivity, electrochemical stability, interfacial compatibility, and cyclic stability, were studied by linear sweep voltammetry, electrochemical impedance spectroscopy and charge/discharge test. It is found that the nano-Al2O3 significantly affect the GPE performances. The optimal content of nano-Al2O3 is 10 wt.%. With using 10 wt.% nano-Al2O3, the ionic conductivity is improved from 1.59×10−3 S.cm−1 to 2.37×10−3 S. cm−1, the decomposition potential is enhanced from 4.8V to 5.2V (vs.Li/Li+) and its interfacial resistance on lithium is reduced from 110 Ω.cm2 to 74 Ω.cm2. (3) P(BMA-co-AN) was mixed with poly(vinylidene fluoride) to prepare a gel polymer electrolyte matrix, P(BMA-co-AN)/PVDF. The performances of the synthesized copolymer and prepared polymer matrixes were characterized with FTIR, TGA, SEM, electrochemical and mechanical testing. With the mixing, the decomposition potential is enhanced from 4.8V to 5.4V (vs.Li/Li+), and its interfacial resistance on lithium is reduced from 110 Ω.cm2 to 52 Ω.cm2. With the application of the (P(BMA-co-AN)/PVDF GPE in lithium ion battery, the battery shows its good cyclic stability.

第一章 绪论 1



1.1 背景 1



1.2锂离子工作原理 2



1.2.1 锂离子电池正极材料 3



1.2.2 锂离子电池负极材料 5



1.2.3 锂离子电池电解液 7



1.3 聚合物锂离子电池 9



1.3.1 聚合物锂离子电池的概念及发展 10



1.3.2 聚合物电解质的特性及分类 10



1.3.3 固体聚合物电解质（SPE）的改进方法 11



1.3.4 凝胶聚合物电解质（GPE） 12



1.4 锂离子电池聚合物电解质改性研究 15



1.4.1 聚合物电解质的问题 15



1.4.2 改变聚合物结构 15



1.4.3 微孔体系 17



1.4.4 纳米复合体系 19



1.4.5 锂盐的改性 20



1.5 本课题的意义及研究内容 21



参考文献 23



第2章 实验部分 29



2.1 电解液的制备 29



2.2 凝胶聚合物电解质的制备 29



2.3 实验和分析方法 29



2.3.1 非电化学方法 29



2.3.2 电化学方法 31



2.4 仪器和试剂 32



2.4.1 仪器 32



2.4.2 试剂 33



参考文献 34



第三章 聚合物P（BMA-CO-AN）的制备和性能研究 35



3.1 引言 35



3.2 制备方法 35



3.3聚合物P（BMA-CO-AN）基GPE的性能表征 36



3.3.1不同单体比例对P（BMA-co-AN）聚合物膜吸液率的影响 36



3.3.2聚合物P（BMA-co-AN）的FTIR光谱图解 37



3.3.3不同溶剂体系的选择对聚合物膜的外貌影响 38



3.3.4 聚合物P（BMA-co-AN）膜的离子电导率 39



3.3.5聚合物膜的DTA/TG研究 39



3.3.6聚合物膜的电化学性能研究 40



3.3.7GPE与锂界面稳定性分析 41



3.3.8 电池循环稳定性能 42



3.4总结 43



参考文献 43



第四章 掺杂纳米AL2O3对聚合物P（BMA-CO-AN）凝胶聚合物性能改善研究 46



4.1引言 46



4.2制备方法 47



4.3 P（BMA-CO-AN）掺杂纳米AL2O3含量的确定 47



4.4掺杂纳米AL2O3聚合物P（BMA-CO-AN）膜的研究 48



4.4.1掺杂聚合物膜的形貌 48



4.4.2掺杂聚合物膜的导电性能 49



4.4.3P(BMA-co-AN)的TGA研究 50



4.5掺杂聚合物电解质的电化学性能 51



4.6 GPE与锂界面稳定性分析 52



4.7 电池循环稳定性能 53



4.8 结论 53



参考文献 54



第五章 聚合物P（BMA-CO-AN）与PVDF复合电解质性质的研究 56



5.1 引言 56



5.2 制备方法 57



5.3聚合物膜的吸液率测试 57



5.4聚合物膜的热重/差热测试 58



5.5 聚合物膜的扫描电镜测试 59



5.6 电化学性能研究 60



5.6.1 聚合物电解质的电化学窗口测试 60



5.6.2聚合物电解质与金属Li的界面相容行研究 61



5.6.3 聚合物电解质锂离子电池倍率性能 62



5.6.4 聚合物电解质锂离子电池循环性能 63



5.7 结论 64



参考文献 64



第六章 结论与展望 67



6.1 结论 67



6.2 展望 68



致 谢 69



作者攻读学位期间发表的学术论文目录 70