电动车用锂离子电池的一致性研究

发布时间：2018-05-24 14:56

本文选题：电动汽车 + 锂离子电池　；参考：《北京科技大学》2017年博士论文

【摘要】：目前,锂离子电池是电动汽车用最为广泛和可靠的动力源。伴随着电动汽车的发展,锂离子电池的安全性、能量密度、寿命和可靠性等使用性能不断得到提升,但与内燃机相比,仍有很大的差距。电池的一致性问题是直接或间接影响的重要因素。而且,电池包中电池单体越多,一致性的影响越突出。因此,提高电池的一致性是改善电池使用性能、促进电动汽车普及的关键技术之一。对锂离子电池而言,在空间维度上,其制备是个多工序集合、多因素控制的过程,存在着关键控制因素,关键控制参数阈值很难辨识和确定的困难;在时间维度上,其在整个使用生命周期内的一致性呈现动态变化的特征。这两个维度上的叠加,导致电池的一致性问题是个多因素耦合的复杂的学术化和工程化交叠的课题。本论文中,我们按照认识问题、分析问题、临时解决问题方法和根本解决方法的步骤对该课题进行研究。主要研究和成果如下:1.利用固体电解质膜(SEI:solid electrolyte interface)增长模型解析出了影响电池全生命周期内一致性的关键参数-自放电率(k_(OCV)),并通过实验得到可靠的验证(论文第4章4.1节)。2.基于上述结论和电池串并联成组使用中电流的分配模型,本论文提出了容量分组和自放电率分组相结合的分组方法,不仅可以提高电池一致性,同时能有效地降低分选成本(论文第4章4.2节)。3.基于阻抗谱理论解析出了影响电池一致性的热力学和动力学因素,并与电池电极的设计参数和工艺参数进行了关联研究,发现影响影响电池一致性的根源是电极的设计和生产控制,进个步通过半电池法分清正极和负极的贡献权重(论文第5章)。4.通过阻抗谱模型,包括团聚体阻抗谱模型和多孔电极阻抗谱模型研究了影响电池一致性的原材料和电极的关键参数,并对这些因素,比如电解液电导率σe,团聚体颗粒半径R_(sp),一次颗粒半径R_(pp)和电荷转移反应交换电流密度i_0在不同温度下的影响权重进行了排序(论文第6章)。有别于其它电池一致性方面的研究,本论文基于作者多年的工程实践经验,样本量大,其贯穿从原料到设计、生产、分选、使用的全生命周期;通过模型找到的用自放电率代替老化的筛选方法能够极大地缩短筛选时间;用理论模型解析出的电池设计端参数与一致性的关联关系,能够知道电池设计与生产工艺开发,提高电池一致性。
[Abstract]:At present, lithium ion battery is the most widely and reliable power source for electric vehicles. With the development of electric vehicles, the safety, energy density, life and reliability of lithium-ion batteries have been improved, but compared with the internal combustion engine, there is still a big gap. Battery consistency is an important factor directly or indirectly. In addition, the more battery cells in the battery package, the more the impact of consistency. Therefore, improving battery consistency is one of the key technologies to improve battery performance and promote the popularity of electric vehicles. For lithium-ion battery, in space dimension, its preparation is a multi-process set, multi-factor control process, there are key control factors, the threshold of key control parameters is difficult to identify and determine; in the time dimension, Its consistency throughout the use life cycle presents a dynamic feature. The superposition of these two dimensions leads to the problem of battery consistency, which is a complicated academic and engineering overlapping subject of multi-factor coupling. In this paper, we study the problem according to the steps of recognizing the problem, analyzing the problem, solving the problem temporarily and solving the problem. The main research and results are as follows: 1. Using the solid electrolyte membrane SEI: solid electrolyte interface growth model, the key parameter which affects the consistency of the battery throughout its life cycle, the self-discharge rate, is analyzed and verified by experiments (Chapter 4, Section 4.1. 2. 2). Based on the above conclusions and the current distribution model in series-parallel battery groups, this paper proposes a combination of capacity grouping and self-discharge rate grouping, which can not only improve the battery consistency. At the same time, it can effectively reduce the sorting cost (Chapter 4, Section 4.2. 3. Based on the impedance spectrum theory, the thermodynamic and kinetic factors affecting the battery consistency are analyzed, and the correlation with the design parameters and process parameters of the battery electrode is studied. It is found that the root of the cell consistency is the electrode design and production control, and the contribution weight of positive and negative electrodes is determined by semi-battery method (Chapter 5, Chapter 4). The key parameters of the raw materials and electrodes that affect the battery consistency are studied by means of the impedance spectrum model, including the agglomerate impedance spectrum model and the porous electrode impedance spectrum model. For example, the electrolyte conductivity 蟽 _ e, aggregate particle radius R _ S _ p _ p, primary particle radius R _ p _ p) and charge transfer reaction exchange current density I _ 0 are sorted at different temperatures (Chapter 6). Different from other battery consistency research, this paper based on the author's engineering practice experience, the sample size is large, which runs through the whole life cycle from raw material to design, production, separation and use; The screening method with self-discharge rate instead of aging can greatly shorten the screening time by using the model, and the relationship between the parameters of the battery design end and the consistency can be obtained by using the theoretical model, and the battery design and production process development can be known. Improve battery consistency.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM912;U469.72

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