【作者】 梁银峥；

【导师】 邱夷平； 张向武；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2011， 博士

【摘要】 可充电锂离子电池具有比能量大,工作电压高,循环寿命长,无记忆效应,安全性能好且能快速充放电等优点,因此近年来成为新型电源技术研究的热点。隔膜是锂离子电池的重要组成部分,在电池中起着隔离正、负电极并使电池内的电子不能自由穿过,但允许电解液中的离子在正负电极间自由通过的作用。隔膜性能的优劣决定电池的界面结构、内阻等,直接影响电池的容量、循环性能以及安全性能等特性。性能优异的隔膜对提高电池的综合性能具有重要的作用。本论文主要研究用静电纺丝法制备和改性先进锂离子电池隔膜材料,包括以下几个部分的内容：(1)用静电纺丝和高温固相反应相结合的方法以及溶胶-凝胶法制备钙钛矿型锂快离子导体陶瓷纳米材料锂镧钛氧化物LLTO；(2)静电纺锂镧钛氧化物La0.55Li0.35TiO3(简称LLTO)/聚丙烯腈Polyacrylonitrile(简称PAN)复合纤维膜的制备及其电化学性能的研究；(3)静电纺磷酸锂铝钛Li1.4Al0.4Ti1.6(PO4)3(简称LATP)/PAN复合纤维膜的制备及其电化学性能的研究；(4)静电纺聚偏氟乙烯Polyvinylidene Fluoride(简称PVDF)纤维改性商用Celgard 2400聚丙烯微孔隔膜的研究。本论文采用静电纺丝和高温固相反应相结合的方法以及溶胶-凝胶法等两种方法制备钙钛矿型锂快离子导体陶瓷纳米材料锂镧钛氧化物LLTO。将这两种方法制备的钙钛矿型锂快离子导体陶瓷纳米材料锂镧钛氧化物LLTO的晶相结构、微观形貌和电导率等进行了对比。结果发现,与静电纺丝和高温固相反应相结合的方法相比,用溶胶-凝胶法合成样品的X射线衍射(X-Ray Diffraction)图谱的杂峰较少,样品的颗粒均匀,有轻微的团聚现象,且具有较高的离子电导率,因此本课题选用溶胶-凝胶法制备锂快离子导体陶瓷纳米材料。用静电纺丝法制备含不同钙钛矿型锂快离子导体陶瓷纳米颗粒锂镧钛氧化物LLTO质量百分比(0%、5%、10%和15%)的LLTO/PAN复合纤维膜。测试了静电纺LLTO/PAN复合纤维膜的电解液吸液率,发现随着钙钛矿型锂快离子导体陶瓷纳米颗粒锂镧钛氧化物LLTO含量的增加,静电纺LLTO/PAN复合纤维膜的电解液吸液率略微增加。对电解液浸润的静电纺LLTO/PAN复合纤维膜的锂离子电导率、电化学稳定窗口以及与金属锂电极的界面阻抗进行了研究,结果发现随着钙钛矿型锂快离子导体纳米陶瓷颗粒锂镧钛氧化物LLTO质量百分含量的增加,电解液浸润的静电纺LLTO/PAN复合纤维膜的锂离子电导率增加,电化学稳定窗口增大,与金属锂电极的界面阻抗降低。分别用含钙钛矿型锂快离子导体陶瓷纳米颗粒锂镧钛氧化物LLTO质量百分比为10%的静电纺LLTO/PAN复合纤维膜、静电纺PAN纤维膜和商用Celgard 2400聚烯烃微孔膜作隔膜,以磷酸铁锂LiFePO4为正极,金属锂为负极制备锂离子电池,并测试了制备电池的充放电性能和循环性能。结果表明,含钙钛矿型锂快离子导体陶瓷纳米颗粒锂镧钛氧化物LLTO质量百分比为10%的静电纺LLTO/PAN复合纤维膜的电池与其他锂离子电池相比,具有较高的首周充放电容量和稳定的循环性能。用溶胶-凝胶法制备钠超离子导体型Na Super Ionic Conductor(简称NASICON)锂快离子导体纳米陶瓷颗粒磷酸锂铝钛Li1.4Al0.4Ti1.6 (PO4)3(简称LATP)并用静电纺丝法制备含不同NASICON型锂快离子导体纳米陶瓷颗粒磷酸锂铝钛LATP质量百分比(0%、5%、10%和15%)的LATP/PAN复合纤维膜。测试了静电纺LATP/PAN复合纤维膜的电解液吸液率,发现随着NASICON型锂快离子导体陶瓷纳米颗粒磷酸锂铝钛LATP含量的增加,静电纺LATP/PAN复合纤维膜的电解液吸液率略有增加。通过对电解液浸润的静电纺LATP/PAN复合纤维膜的锂离子电导率、电化学稳定窗口以及与金属锂电极的界面阻抗的研究,结果表明随着NASICON型锂快离子导体纳米陶瓷颗粒磷酸锂铝钛LATP质量百分含量的增加,电解液浸润的静电纺LATP/PAN复合纤维膜的锂离子电导率增加,电化学稳定窗口增大,与金属锂电极的界面阻抗降低。用磷酸铁锂LiFePO4作正极,金属锂片作负极,分别用含质量百分比为15%的磷酸锂铝钛LATP静电纺LATP/PAN复合纤维膜,静电纺PAN纤维膜和商用Celgard 2400聚丙烯微孔膜作隔膜制备锂离子电池,并对制备的锂离子电池的充放电性能和循环性能进行测试,结果表明含质量百分比为15%的NASICON型锂快离子导体纳米陶瓷颗粒磷酸锂铝钛LATP静电纺LATP/PAN复合纤维膜的电池较其他电池具有较高的首周充放电容量和良好的循环性能。通过静电纺丝的方法将聚偏氟乙烯(PVDF)沉积到商用Celgard2400聚丙烯微孔隔膜上。用氩常压等离子体对商业用Celgard 2400聚丙烯微孔隔膜进行处理,发现等离子体处理增强了静电纺丝聚偏氟乙烯(PVDF)纤维膜与商业用Celgard 2400聚丙烯微孔隔膜之间的粘结力。对静电纺PVDF/Celgard 2400聚丙烯复合纤维膜的电解液吸液率进行测试,发现用静电纺丝的方法将聚偏氟乙烯(PVDF)以纳米纤维的方式沉积到商业用Celgard 2400聚丙烯微孔隔膜的方法可以明显改善商业用Celgard 2400聚丙烯微孔隔膜与电解液间的亲和性。同时测试了商业用Celgard 2400聚丙烯微孔隔膜和静电纺PVDF/Celgard 2400聚丙烯复合纤维膜的电化学稳定窗口,结果表明静电纺PVDF/Celgard 2400聚丙烯复合纤维膜相较于商业用Celgard2400聚丙烯微孔隔膜,具有较宽的电化学稳定窗口。更多还原

【Abstract】 Rechargeable Lithium-ion batteries (LIBs) have great energy and power density, high working voltage, long cycle life, no memory effect, good safety performance and fast-charging capability, etc., thus they will have become the new power source technology research hotspot in recent years. The separator is a critical component in LIBs and is placed between the positive electrode and the negative electrode to prevent physical contact of the electrodes while enabling free ionic transport and isolating electronic flow. The separator performance quality which determines the battery interface structure, internal resistance etc., directly affects the battery capacity, cycling performance and safety properties and other characteristics. The separator with excellent properties plays a key role in improving the comprehensive performance of the battery.This paper is mainly about the study on using the electrospinning technique to prepare and modified separator materials for the advanced lithium-ion batteries(LIBs), including the following aspects:(1) Electrospinning technique is combined with the high temperature solid-state reaction method and the sol-gel method to prepare the perovskite-type lithium fast ion conductor ceramic nano material lithium-lanthanum -titanate oxide (LLTO); (2) The research on the fabrication and electrochemical characterization of the electrospinning LLTO/PAN composite fibrous membrane for lithium-ion battery separator; (3) The research on the fabrication and electrochemical characterization of the electrospinning LATP/PAN composite fibrous membrane forlithium-ion battery separator; (4) The research on the modification of the Celgared 2400 polypropylene microporous membrane by the electrospun PVDF nanofibers.Two methods (the electrospinning technique combined with high temperature solid-state reaction, the sol-gel method) were used to prepare the perovskite-type lithium fast ion conductor ceramic nanoparticles lithium lanthanum titanate oxide (LLTO). The crystal structure, morphology, and the ionic conductivity of the perovskite-type lithium fast ion conductor ceramic nanoparticles lithium lanthanum titanate oxide (LLTO) which was prepared by these two methods were characterized and measured. The results demonstrated that the samples prepared by the sol-gel method can get relatively pure crystalline phase and have uniform particle size, slight agglomeration and relatively high ionic conductivity.The electrospinning technique was used to prepare the LLTO/PAN composite fiber membrane with different lithium lanthanum titanate oxide (LLTO) content (0%,5%,10% and 15%). The electrolyte uptake of the electrospun LLTO/PAN composite fiber membranes was tested and found that with an increase of the perovskite-type lithium fast ion conductor ceramic nano material lithium lanthanum titanate oxide (LLTO) content, the electrolyte uptake of the electrospun LLTO/PAN composite fiber membranes slightly increased. When the lithium ion conductivity, the electrochemical stability window and the interface resistance of the electrolyte-soaked electrospun LLTO/PAN composite fiber membrane were tested, it was found that as the perovskite-type lithium fast ion conductor ceramic nano material lithium lanthanum titanate oxide LLTO content increased, the electrospun LLTO/PAN composite fiber-based membranes had higher lithium ion conductivity, higher electrochemical stability window, and lower interfacial resistance with lithium electrode. In addition, lithium//1 M LiPF6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes used as the separator have exhibited good charge/discharge capacity and cycle performance.Using the sol-gel method to prepare the NASICON-type lithium fast ion conductor ceramic nanoparticles lithium aluminum titanium phosphate (LATP).The electrospinning technique was used to prepare the LATP/PAN composite fiber membrane with different LATP content (0%,5%,10% and 15%). The electrolyte uptake of the electrospun LATP/PAN composite fiber membranes was tested and the results showed as the NASICON-type lithium fast ion conductor ceramic nano material lithium aluminum titanium phosphate (LATP) content increase, the electrolyte uptake of electrospun LATP/PAN composite fiber membranes slightly increase. The lithium ion conductivity, the electrochemical stability window and the interface resistance of the electrolyte-soaked electrospun LATP/PAN composite fiber membrane were also measured and the consequence exhibited that as the NASICON-type lithium fast ion conductor ceramic nano material lithium aluminum titanium phosphate (LATP) content increase, the electrospun LATP/PAN composite fiber-based membranes had higher lithium ion conductivity, higher electrochemical stability window, and lower interfacial resistance with lithium electrode. Additionally, lithium//1 M LiPF6/EC/EMC//lithium iron phosphate cells including LATP/PAN composite fiber-based membranes utilized as the separator demonstrated good charge/discharge capacity and cycle performance.Use the electrospinning technique to deposite the PVDF onto the Celgard 2400 polypropylene microporous membrane. The argon atmospheric pressure plasma technique was used to treat the Celgard 2400 polypropylene microporous membrane, which can improve the adhesion between the electrospun PVDF fiber and the Celgard 2400 polypropylene microporous membrane. The electrolyte uptake of electrospun PVDF/Celgard 2400 polypropylene composite membrane was checked and it was found that the elecrospun PVDF fiber can greatly improved the affinity between the Celgard 2400 polypropylene microporous membrane and the electrolyte. Finally, the electrochemical stability window of the commercial Celgard 2400 polypropylene microporous membrane and the electrospun PVDF/Celgard 2400 polypropylene composite membrane was tested and the results showed that the electrospun PVDF/Celgard 2400 polypropylene composite membrane had relatively wider electrochemical stability window than the commercial Celagard 2400 polypropylene microporous membrane.更多还原