间位芳纶纳米纤维基锂电池隔膜的制备及其性能研究

发布时间：2018-06-08 16:04

  本文选题：静电纺丝 + 锂离子电池　； 参考：《东华大学》2016年硕士论文

【摘要】：锂离子电池作为一种高能电源,其具有能量密度大、使用寿命长、可快速充放电等特点,在通信、民生和国防等领域被广泛的应用。在锂电池的结构中,隔膜作为关键的内层组件之一,其作用在于隔离电池正负极,同时为锂离子的迁移提供通道,因此隔膜性能的优劣直接影响到锂离子电池的电化学性能和安全性能。商品化聚烯烃类隔膜由于较低的成本、优异的机械性能和良好的电化学稳定性而被广泛的应用在锂电池隔膜中,但其对电解液浸润性差,且高温受热时形变大,严重制约了锂电池的发展与应用。采用静电纺丝法制备的纳米纤维膜具有纤维直径小、孔隙率高和聚合物原料选择灵活等特点,为锂离子电池隔膜的制备提供了新的途径。当前在静电纺锂电池隔膜领域已取得了一些可喜的研究成果,但锂电池隔膜还普遍存在着力学性能较差和耐高温性差的缺点。本文通过选用间位芳纶(PMIA)和聚氨酯(PU)作为原料,结合两种材料各自的优点,通过静电纺丝技术制备出PMIA基纳米纤维膜,并对其理化性能、电化学和电池性能进行研究,旨在获得综合性能优异的锂电池隔膜。首先我们选用N,N-二甲基乙酰胺(DMAc)/LiCl作为溶剂,配制出浓度为15wt%的PMIA纺丝溶液,通过静电纺丝法制备出了PMIA纳米纤维膜,并对其用于锂电池隔膜进行了初步探讨。研究结果表明:PMIA优异的机械性能使得PMIA隔膜具有高达24.25MPa的拉伸强度;PMIA良好的耐热性赋予了PMIA隔膜优异的热稳定性;相比Celgard隔膜,PMIA隔膜高的孔隙率及出色的电解液浸润性使其拥有较高的离子电导率和宽的电化学稳定窗口;此外,在0.2C倍率下,PMIA隔膜组装的Li/LiCoO2电池表现出良好的循环稳定性。此外,我们采用溶液共混静电纺丝技术制备出了四种不同质量比的PMIA-PU共混纳米纤维膜,并对其用于锂电池隔膜进行了深入的研究。研究结果表明:静电纺纳米纤维膜所具有的高孔隙率、PU的引入和纳米蛛网结构使所制得的PMIA-PU共混隔膜具有高拉伸强度(15.79MPa)和高达1.38mS/cm的离子电导率;PMIA的引入赋予了共混隔膜优异的热稳定性、阻燃性和出色的电解液浸润性,共混隔膜在180℃加热0.5h后几乎未发生热收缩现象,有利于提高锂电池的安全性能;同时,PMIA-PU共混隔膜高达5.1V的电化学稳定窗口能够满足锂离子电池在工作电压范围内正常工作的需求;此外,与商品化Celgard隔膜相比,共混隔膜组装的Li/LiFePO4电池在0.2C倍率下循环65次后具有高的容量保持率(96.29%)以及拥有良好的倍率放电性能,使其能够满足锂离子电池的应用需求。
[Abstract]:As a kind of high energy power supply, Li-ion battery is widely used in communication, people's livelihood and national defense because of its high energy density, long service life, rapid charge and discharge and so on. In the structure of lithium battery, the diaphragm is one of the key inner components, its function is to isolate the positive and negative electrodes of the battery and to provide the channel for the migration of lithium ion. Therefore, the performance of diaphragm directly affects the electrochemical performance and safety performance of lithium ion battery. Commercial polyolefin membranes are widely used in lithium battery membranes due to their low cost, excellent mechanical properties and good electrochemical stability. The development and application of lithium battery are seriously restricted. The nanofiber membrane prepared by electrospinning has the advantages of small fiber diameter, high porosity and flexible selection of polymer raw materials, which provides a new way for the preparation of lithium ion battery membrane. At present, some gratifying research results have been obtained in the field of electrostatic spinning lithium battery diaphragm, but the disadvantages of poor mechanical properties and poor heat resistance of lithium battery diaphragm still exist in general. In this paper, PMIA based nanofiber films were prepared by electrospinning technology, and their physical and chemical properties, electrochemical and battery properties were studied by using m-aramid (PMIA) and polyurethane (PUU) as raw materials and combining the respective advantages of the two materials. The aim is to obtain lithium battery diaphragm with excellent comprehensive performance. In this paper, the PMIA nanofilament membrane was prepared by electrospinning method, and the PMIA nanofilament membrane was prepared by electrostatic spinning method, and the PMIA nanofilament membrane was prepared by electrostatic spinning method. The PMIA nanofilament membrane used in lithium battery membrane was discussed preliminarily in this paper, which was used as the solvent for the preparation of PMIA / LiCl solution with a concentration of 15 wt%. The results show that the excellent mechanical properties of the PMIA membrane make the PMIA membrane have tensile strength up to 24.25 MPA and the excellent thermal stability of the PMIA diaphragm is attributed to the excellent thermal stability of the PMIA diaphragm. Compared with Celgard membrane, PMIA membrane has high porosity and excellent electrolyte wettability, and has high ionic conductivity and wide electrochemical stability window. In addition, the Li- / LiCoO2 cell assembled with PMIA membrane exhibits good cycling stability at 0.2C ratio. In addition, four kinds of PMIA-PU nanofiber membranes with different mass ratios were prepared by solution blending electrospinning technique, and their application in lithium battery membranes was studied. The results show that the introduction of high porosity pu and the structure of nano-cobweb make the PMIA-PU blend membrane have high tensile strength (15.79MPa) and ionic conductivity up to 1.38mSpcm (PMIA). Excellent thermal stability of the mixed membrane, The flame retardancy and the excellent electrolyte wettability, the heat shrinkage phenomenon of the blend membrane almost did not occur after heating at 180 鈩，

本文编号：1996375