摘 要

在电动汽车行业前景广阔的当下，锂电池凭借其能量密度高、功率密度高及较长使用寿命的优点成为电动汽车核心电池技术中最成熟、应用最广的研究热点。而作为制约锂电池发展的首要问题，电池老化带来的诸如容量衰退、寿命缩短等难题限制了电动汽车的推广与锂离子电池技术的进步。本文的目的是研究锂离子电池老化规律并诊断健康状态。本文的研究内容如下：

（1）简述了锂电池的组成、反应原理并举例说明了锂离子的迁移过程。对锂离子电池的老化过程进行了简要分析，并总结了影响锂电池老化过程的外部因素与内部因素。

（2）介绍了三种用于分析电池老化机理的方法，并阐述了这三种方法的原理及优缺点，最后比较三种方法的优缺点，选择利用特性分析法中的增量容量法来解析电池老化机理。然后通过ncm523电池循环老化实验得到的数据，简单分析了锂电池在循环过程中的性能变化及开路电压曲线的特征。再阐述了利用增量容量分析法建立增量容量曲线的过程，并分析曲线里各峰相关特征与电池内部电化学反应的变化关系。

（3）分别比较了锂电池容量增量曲线在不同条件下因单一因素变化而产生的变化，通过解析曲线的差异来建立容量增量曲线与这些影响因素的变化关系，并借助这些影响因素与电池外部特征及内部电化学反应变化的关系，最后可以用容量增量曲线来诊断电池状态。

（4）从容量增量曲线中提取出了可以用于估算电池健康状态的特征参数，再通过关联分析法对比各参数与电池可用容量的关联性，选出与电池可用容量相关性最强的特征参数。介绍了三大类老化模型及其原理优缺点。将选出的容量增量曲线特征参数作为输入变量。

（5）介绍了GA-BP神经网络模型的制作流程与细节。

关键词：锂电池；增量容量分析法；老化模型；老化规律

Abstract

With the bright future of the electric vehicle industry, lithium batteries have become the most mature and widely used research hotspot in the core battery technology of electric vehicles due to their advantages of high energy density, high power density and long service life. As the primary problem restricting the development of lithium batteries, problems such as capacity decline and shortened life caused by battery aging have limited the promotion of electric vehicles and the advancement of lithium-ion battery technology. The purpose of this article is to study the aging rules of lithium-ion batteries and diagnose their health status. The research contents of this article are as follows:

(1) Briefly introduce the composition and reaction principle of lithium battery and illustrate the migration process of lithium ion. The aging process of lithium-ion batteries is briefly analyzed, and the external and internal factors that affect the aging process of lithium batteries are summarized.

(2) Introduce three methods for analyzing the aging mechanism of the battery, and explain the principles, advantages and disadvantages of the three methods, and finally compare the advantages and disadvantages of the three methods, choose to use the incremental capacity method in the characteristic analysis method to Analyze the battery aging mechanism. Then through the data obtained by the ncm523 battery cycle aging experiment, the performance changes of the lithium battery during the cycle and the characteristics of the open circuit voltage curve are simply analyzed. The process of establishing the incremental capacity curve using the incremental capacity analysis method is further elaborated, and the relationship between the correlation characteristics of each peak in the curve and the electrochemical reaction inside the battery is analyzed.

(3) Compare the changes of the capacity increase curve of the lithium battery due to the change of a single factor under different conditions, and establish the relationship between the capacity increase curve and these influencing factors by analyzing the differences of the curves, and use these influencing factors and The relationship between the external characteristics of the battery and the changes in the internal electrochemical reaction can finally be used to diagnose the battery status using the capacity increase curve.

(4) The characteristic parameters that can be used to estimate the health status of the battery are extracted from the capacity increment curve, and then the correlation between each parameter and the available capacity of the battery is compared by the correlation analysis method, and the strongest correlation with the available capacity of the battery is selected. Characteristic Parameters. Three types of aging models and their advantages and disadvantages are introduced. Use the selected characteristic parameters of the capacity increment curve as input variables.

(5) Introduced the production process and details of the GA-BP neural network model.

Key Words：Lithium battery; incremental capacity analysis; aging model; aging law

目录

第1章绪论 1

1.1选题背景及意义 1

1.2研究的目的 1

1.3国内外的研究现状分析 1

第2章简析锂离子电池 3

2.1锂离子电池的介绍 3

2.2锂离子电池老化机理分析 3

2.2.1影响锂离子电池的内部原因 3

2.2.2影响锂离子电池的外部原因 4

第3章锂离子电池寿命老化试验及SOH估算 5

3.1锂离子电池循环性能分析 6

3.1.1电池容量变化 6

3.1.2开路电压曲线变化 7

3.2锂离子电池ICA分析 7

3.2.1容量增量分析法原理及影响因素分析 7

3.2.2锂离子电池IC曲线影响因素 9

3.2.2.1不同充电电流倍率对容量增量曲线影响的差异 9

3.2.2.2不同温度对容量增量曲线影响的差异 10

3.2.2.3不同老化程度对容量增量曲线影响的差异 12

3.3锂电池SOH估算 13

3.3.1提取估算电池健康状态的容量增量曲线特征参数 13

3.3.2各曲线特征参数与电池老化的相关性计算 14

第4章老化模型 16

4.1老化模型分类 16

4.2选取老化模型 17

4.2.1介绍BP（back propagation）神经网络 17

4.2.1.1 BP神经网络具备的能力 17

4.2.1.2 BP神经网络的构成 17

4.2.1.3 BP神经网络的训练过程 20

4.2.2介绍算法 21

4.2.2.1遗传算法 21

4.2.2.2遗传算法的运转过程 23

4.3设计模型 24

4.3.1利用遗传算法对神经网络进行优化 24

4.3.2模型的建立和参数的选择 25

结论 27

参考文献 28

致 谢 30

第1章绪论

1.1选题背景及意义

在当今世界上，新能源汽车成为了汽车行业从业人员绕不开的话题。这里面既有传统化石燃料短缺的问题，如2010年的《BP世界能源统计》显示，截至2009年年底，全球已探明的石油储量为13331亿桶，以2009年的开采速度可开采45.7年^[10]；又与环保问题有关，如我国将环保写入基本国策。这些都是鞭策新能源汽车的成长重要因素。而电动汽车作为目前最接近替代传统汽车地位和技术最成熟的项目，遭受了资本的追捧与政府的大力扶持。如李克强总理在2016年2月24日召开的国务院常务会议上明确强调“支持发展新能源汽车等战略性新兴产业，加快实现动力电池革命性突破” ^[10]；彰显了我国对电动车辆研发与大规模应用的重视。在这种背景下，制约电动汽车推广应用的最大问题——动力电池技术就变得格外值得研究摸索。

在这种情况下，具有比能量高、无记忆效应、自放电低、循环性能好等优点的锂离子电池从电动汽车动力电池中脱颖而出成为主导电源。不过锂离子电池老化对寿命的影响时阻碍锂电池发展是一大难题，完善了这一环节才能在电动汽车产业的发展上有所建树。