高性能锂电池聚合物电解质的原位制备与性能研究

发布时间：2018-05-12 22:12

本文选题：聚合物电解质 + 聚氰基丙烯酸乙酯　；参考：《青岛科技大学》2017年硕士论文

【摘要】：目前,人们对高安全性高能量密度锂离子电池的需求越来越高,聚合物电解质锂电池与液态电解质锂离子电池相比具有更高的能量密度和更好的安全性能,因而受到研究人员的广泛关注。以往的聚合物电解质制备方法大多采用复杂的非原位法制备,这些方法需要消耗大量的有机溶剂用于锂盐的和聚合物的溶解。后续的膜制备和溶剂蒸发使这个方法不仅复杂而且污染环境,面临消耗更多材料,成本昂贵。所以研究简单的原位合成方法来制备聚合物电解质变得十分迫切。本论文采用原位阴离子聚合和原位阳离子聚合两种方式分别制备了高性能聚氰基丙烯酸乙酯聚合物电解质和交联聚乙二醇二缩水甘油醚全固态聚合物并研究了其电化学性能,具体内容如下:(1)运用金属锂引发阴离子原位聚合制备了耐5 V高电压聚氰基丙烯酸乙酯基聚合物电解质。此种方法充分利用了氰基丙烯酸乙酯结构中含有强吸电子基团氰基和酯基,活化能低的优点,采用金属锂作为阴离子引发剂来引发氰基丙烯酸乙酯进行聚合。此种聚合方法简单高效,成功制备了新型聚合物电解质。通过对聚氰基丙烯酸乙酯基聚合物电解质进行电化学性能研究可知,此电解质的电导率可以达到2.7×10-3 S cm-1,电化学稳定窗口为4.8 V vs.Li+/Li,并且电解质可以渗透到正极材料内,产生良好的界面稳定性,并且,聚氰基丙烯酸乙酯电解质在磷酸铁锂和高电压镍锰酸锂电池中具有良好的倍率性能,循环稳定性。因此,聚氰基丙烯酸乙酯反应条件温和,机械强度好,是一种非常有潜力应用于耐5 V高电压柔性锂电池。(2)利用锂盐的路易斯酸性引发阳离子原位聚合,制备了高性能聚乙二醇二缩水甘油醚全固态聚合物电解质。将液态聚乙二醇二缩水甘油醚作为聚合物前驱体,双氟草酸硼酸锂作为引发剂,双三氟甲基磺酰亚胺锂作为锂盐,通过原位聚合的方法成功制备了全固态聚合物电解质。相对于传统的制备方法,此固态聚合物电解质体系中没有添加额外的引发剂或催化剂,只含有前驱体和锂盐,体系内成分简单。通过低温加热的原位制备方法不仅制备方法可靠简单,且其相对于其他的聚合方法也能够抑制副反应的发生。而且此种化学交联的方法制备的交联PEO基聚合物电解质具有较低的玻璃化转变温度,使电解质具有较高的室温离子电导率(8.9×10-5 S cm-1)。此外,该原位交联PEO基聚合物电解质在磷酸铁锂半电池中具有良好的倍率性能,循环稳定性,并能够抑制锂枝晶的产生。因此,通过锂盐自催化法制备交联PEO聚合物电解质是一种非常有潜力的电解质制备方法。
[Abstract]:At present, the demand for high safety and high energy density lithium ion batteries is getting higher and higher. The polymer electrolyte lithium battery has a higher energy density and better safety performance compared with the liquid electrolyte lithium ion battery. Therefore, the researchers pay much attention to the high energy density and the lithium ion battery. In situ preparation, these methods require a large amount of organic solvents to be used for lithium salts and the dissolving of polymers. Subsequent membrane preparation and solvent evaporation make this method not only complex but also pollute the environment, so it is expensive to consume more materials, so it is very pressing to study a simple in situ synthesis method to prepare polymer electrolytes. In this paper, high performance polyethyl cyanoacrylate polymer electrolyte and crosslinked polyethylene glycol two glycidyl ether all solid state polymer were prepared by in situ anionic polymerization and in situ cationic polymerization, and their electrochemical properties were studied. The specific contents are as follows: (1) the anionic in-situ polymerization was initiated by lithium metal (1). The 5 V high voltage Polycyanoacrylate based polymer electrolyte is prepared. This method makes full use of the advantages of the cyanoacrylate and ester group with strong absorption group in the structure of ethyl cyanoacrylate, and the activation energy is low. The lithium cyanoacrylate is polymerized by metal lithium as an anionic initiator. This polymerization is simple and efficient. A new polymer electrolyte was successfully prepared. By studying the electrochemical performance of the Polycyanoacrylate based polymer electrolyte, the conductivity of the electrolyte can reach 2.7 x 10-3 S cm-1, the electrochemical stability window is 4.8 V vs.Li+/Li, and the electrolyte can penetrate into the cathode material and produce good interfacial stability. Moreover, the Polycyanoacrylate electrolyte has good multiplier performance and cycle stability in lithium iron phosphate and high voltage lithium manganate batteries. Therefore, the reaction conditions of Polycyanoacrylate are mild and the mechanical strength is good. It is a very potential application to the 5 V high voltage flexible lithium battery. (2) the Lewis acid introduction of lithium salt. A high performance polyethylene glycol two glycidyl ether all solid state polymer electrolyte was prepared by cationic in situ polymerization. The liquid polyethylene glycol two glycidyl ether was used as polymer precursor, difluorooxalic acid lithium borate as an initiator, and difluoromethyl sulfonimide lithium as lithium salt. The solid state polymerization was successfully prepared by in-situ polymerization. Compared with traditional preparation methods, there is no additional initiator or catalyst in this solid-state polymer electrolyte system, which contains only precursors and lithium salts, and the internal composition of the system is simple. The preparation method by in situ preparation by low temperature heating is not only reliable and simple, but also can be inhibited relative to other polymerization methods. In addition, the crosslinked PEO based polymer electrolyte prepared by this chemical crosslinking method has a lower glass transition temperature and a high ionic conductivity (8.9 * 10-5 S cm-1) at room temperature. In addition, the in-situ crosslinked PEO based polymer electrolyte has good multiplier performance in the iron phosphate half battery. Therefore, the preparation of the crosslinked PEO polymer electrolyte by the lithium salt autocatalytic method is a very potential method for the preparation of electrolyte.

【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ317;TM912

【参考文献】