静电纺丝法制备交联聚酰亚胺纤维膜及其作为锂电隔膜的应用研究

发布时间：2018-03-11 19:22

本文选题：静电纺丝　切入点：锂离子电池隔膜　出处：《北京化工大学》2014年硕士论文　论文类型：学位论文

【摘要】：锂离子电池产业近几年成为具有广阔前景的朝阳产业。越来越多锂离子电池的主要材料被产业化制备,越来越多的锂电课题被攻关。但是,近些年发生的锂离子电池爆炸等不安全现象也引起了广泛关注,安全问题急需解决。一般来说,很多锂离子电池发生爆炸现象都是由于锂离子电池内部出现过热现象,而过热现象可以由很多条件引发,例如,过充电、微短路、使用环境不当等。在过高温度下,锂电隔膜起不到有效地隔离锂电正负极的作用,从而引发爆炸。现行商业化聚烯烃锂离子电池隔膜强度高,化学稳定性好,成本低,但是耐高温性差,吸液率低。耐温性差表现在当锂离子电池发生过热现象时易破裂,不能有效隔离电池正负极,引发爆炸。吸液率低不利于提高锂电池的充放电容量的提高,限制了其大电流充放电性能。因此,对一种耐高温、吸液能力强的锂电隔膜的需求迫在眉睫。电纺制备的无纺布纤维膜具备均匀的多孔结构,与锂电隔膜的微孔结构类似。聚酰亚胺作为一种工程塑料,其具有高强高模、耐高低温、耐辐射、耐溶剂和尺寸稳定性等优良性能,但是传统热固性聚酰亚胺的溶解性差,限制了其加工性。聚醚酰亚胺是一种热塑性聚酰亚胺,一方面继承了聚酰亚胺材料的优异性能,而且其加工多样性好,可溶液加工,可熔融加上。开且,聚醚酰亚胺体系目前已经实现产业化生产,原料来源广泛且稳定,有利于聚醚酰亚胺系列产品产业化的实现。本文首先通过静电纺丝法制备了无纺布聚酰亚胺纤维膜,然后采用热致微交联工艺,使无纺布纤维膜的相邻纤维之间产生微熔融,从而在纤维膜中引入交联点,实现纤维之间的熔接,通过改变工艺参数,制备了具有不同交联形貌的热塑性聚酰亚胺纤维膜,机械强度比无纺布得到了大幅度提高,改善了过于开放的孔结构,提高了制品尺寸稳定性,且孔隙率高,吸液率高,耐高温性好。本文中,将交联聚酰亚胺隔膜应用于锂电隔膜,测试发现其在小电流和大电流充放电密度下均能起到隔离正负极的作用,隔膜充放电寿命长,电化学稳定窗口高,且充放电多次后隔膜孔结构稳定,具有很好的商业应用前景。
[Abstract]:In recent years, Li-ion battery industry has become a promising sunrise industry. More and more main materials of Li-ion battery have been industrialized, and more and more lithium electric problems have been solved. In recent years, unsafe phenomena such as lithium ion battery explosion have also aroused widespread concern, and safety problems need to be solved urgently. Generally speaking, many lithium ion batteries explosion phenomenon is due to the phenomenon of overheating inside the lithium ion battery. The phenomenon of overheating can be caused by many conditions, such as overcharging, micro-short circuit, improper use of the environment, etc. At too high temperature, the lithium diaphragm can not effectively isolate the positive and negative electrodes of lithium. The current commercial polyolefin lithium-ion battery has high strength, good chemical stability, low cost, but poor high temperature resistance and low liquid absorption. It can not effectively isolate the positive and negative electrodes of the battery and cause explosion. The low absorption rate is not conducive to increasing the charge and discharge capacity of the lithium battery and limits its high current charge-discharge performance. The demand of lithium electric separator with strong absorbency is urgent. The non-woven fiber membrane prepared by electrospinning has a uniform porous structure, similar to the micropore structure of the lithium electric diaphragm. As an engineering plastic, polyimide has high strength and high modulus, high temperature resistance and radiation resistance. Good properties such as solvent resistance and dimensional stability, but the poor solubility of traditional thermosetting polyimide limits its processability. Polyetherimide is a thermoplastic polyimide, which inherits the excellent properties of polyimide materials. In addition, the polyetherimide system has been produced in a wide and stable source, which is beneficial to the industrialization of polyetherimide products. In this paper, the non-woven polyimide fiber membrane was prepared by electrospinning method, and then the micro-crosslinking process was adopted to make the adjacent fibers of the non-woven fiber membrane micro-melt, so that the cross-linking point was introduced into the fiber membrane. The thermoplastic polyimide fiber membrane with different cross-linking morphology was prepared by changing the technological parameters. The mechanical strength of the film was greatly improved than that of the non-woven fabric, and the pore structure which was too open was improved. The product has high porosity, high liquid absorption and high temperature resistance. In this paper, the cross-linked polyimide membrane is applied to the lithium electric separator. It is found that it can isolate positive and negative electrodes at low current and high current charge / discharge densities. The diaphragm has long charge and discharge life, high electrochemical stability window, and stable pore structure after charging and discharging many times, so it has a good commercial application prospect.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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