梯次利用锂离子电池容量和内阻变化特性研究

发布时间：2018-06-30 16:51

本文选题：梯次利用电池 + 容量衰退机理　；参考：《北京交通大学》2014年硕士论文

【摘要】：摘要：车用淘汰锂离子电池的梯次利用,是降低动力电池全寿命周期成本,提升电池的利用价值的有效手段。车用淘汰电池的再循环寿命是制约电池梯次利用的关键问题之一。本文从梯次利用电池再循环过程中的衰退机理角度出发,主要致力于研究梯次利用电池容量和内阻的再循环特性及其之间的相互关系,具体研究内容及结论如下： (1)深入分析了不同充放电倍率应力和SOC循环区间应力下电池欧姆内阻和极化内阻的再循环特性,并利用多重线性回归的方法建立了不同SOC循环区间应力下电池的欧姆内阻、极化内阻增长率和全区间电池欧姆内阻、极化内阻增长率之间的函数模型,与实际全区间循环的对应数据对比验证了该模型的有效性,减少了电池寿命预测的时间成本。 (2)量化分析了电池再循环过程中的热力学损失和动力学损失,结果显示梯次利用电池再循环使用时,锂离子和活性材料的损失是电池容量损失的主要部分,并且历史使用路径的差异性对电池再循环使用过程中容量的衰退方式会产生深远影响,旧电池很可能会出现一些异常于新电池的现象。利用容量增量(ICA)分析方法,对比分析了梯次利用电池在倍率、SOC循环区间与循环老化相互耦合作用下的电池容量衰退机理及材料退化规律。建立了基于退化轨迹的梯次利用电池寿命预测模型,该模型确定了梯次利用电池寿命与SOC循环区间应力的数学关系,这对于储能工况下梯次利用电池循环寿命的预测具有重要意义。 (3)利用典型相关分析方法,确立了该批次电池再循环使用过程中容量衰退率和欧姆内阻增长率与极化内阻增长率之间的关系模型,模型具有较高的精度和普适性,8只电池的实验数据一致显示电池的容量衰退率和内阻增长率之间均符合一定的平面关系。 (4)建立了电化学阻抗谱模型,对比分析了新旧电池的电化学特性参数,发现电池老化过程中欧姆内阻,电化学极化阻抗,电双层电容及锂离子的扩散系数与电池健康状态联系密切。对比分析了新旧电池的外特性参数如SOC-OCV曲线、ICA曲线、倍率充放电效率,结果表明SOC-OCV曲线在电池的全寿命周期内并未随电池健康状态的变化发生整体升高和降低的趋势,在实际应用中,应加强对一些恶劣工况下(高低温,大倍率)电池管理系统中SOC-OCV的参数进行定期修正；在电池的衰退过程中,电极材料的损失及动力学特性的变化使得ICA曲线上部分峰的位置,尖锐程度均发生显著改变；当容量衰退率在一定范围内,电池具有良好的倍率特性和充放电效率,但是当容量衰退至50%时,倍率特性和充放电效率显著降低,因此车用淘汰锂离子动力电池梯次利用时,适合投入到一些小倍率充放电的储能工况中。
[Abstract]:Absrtact: it is an effective way to reduce the whole life cycle cost of power battery and to improve the utilization value of battery by eliminating the use of lithium-ion battery. One of the key problems that restrict the utilization of battery ladder is the recirculation life of vehicle battery. In this paper, from the point of view of the degradation mechanism in the process of battery recirculation, this paper is mainly devoted to the study of the recirculation characteristics and the relationship between the capacity and internal resistance of the trapezoidal battery. The specific research contents and conclusions are as follows: (1) the recirculation characteristics of the ohmic and polarized internal resistance of the battery under different charge / discharge rate stress and SOC cycle region stress are analyzed. The multiple linear regression method is used to establish the functional models between the ohmic internal resistance, the polarization internal resistance growth rate, the whole cell ohmic resistance and the polarization internal resistance growth rate under different SOC cyclic region stress. Compared with the corresponding data of the whole cycle, the validity of the model is verified, and the time cost of battery life prediction is reduced. (2) the thermodynamic and kinetic losses during battery recirculation are quantitatively analyzed. The results show that the loss of lithium-ion and active material is the main part of the battery capacity loss. And the difference of the historical usage path will have a profound influence on the decline of the battery capacity in the process of recycling, and the old battery may appear some phenomena that are abnormal to the new battery. By means of capacity increment (ICA) analysis, the degradation mechanism of battery capacity and the law of material degradation are compared and analyzed under the coupling of the ratio SOC cycle interval and the cyclic aging of the trapezoidal battery. In this paper, a prediction model of the life of echelon utilization battery based on degenerate trajectory is established. The mathematical relationship between the life of ladder utilizing battery and the cyclic stress of SOC is determined by the model. It is of great significance to predict the cycle life of the battery under the condition of energy storage. (3) using the canonical correlation analysis method, The relationship between the capacity decline rate, the growth rate of ohmic internal resistance and the growth rate of polarization resistance is established. The experimental data of 8 batteries with high accuracy and universality show that the relationship between the cell capacity decline rate and the growth rate of internal resistance is consistent. (4) the electrochemical impedance spectrum model is established. The electrochemical characteristic parameters of the new and old batteries were compared and analyzed. It was found that the ohmic internal resistance, electrochemical polarization impedance, electric double layer capacitance and diffusion coefficient of lithium ion were closely related to the healthy state of the battery during the aging process. The external characteristic parameters of new and old batteries, such as SOC-OCV curve and ICA curve, are compared and analyzed. The results show that the SOC-OCV curve does not increase or decrease with the change of battery health during the whole life cycle of the battery. In practical application, the parameters of SOC-OCV in the battery management system under some bad working conditions (high and low temperature, large multiplier) should be revised regularly. The loss of electrode material and the change of kinetic characteristics make the position and sharpness of some peaks on ICA curve change significantly, when the capacity decline rate is in a certain range, the battery has good rate characteristics and charge-discharge efficiency. However, when the capacity declines to 50, the rate characteristics and charge / discharge efficiency decrease significantly. Therefore, it is suitable for some small rate charging and discharging energy storage conditions when the lithium ion power battery is eliminated in the trapezoidal use.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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