Current Distribution Measurements in Parallel-Connected Lithium-Ion Cylindrical Cells under Non-Uniform Temperature Conditions
Current Distribution Measurements in Parallel-Connected Lithium-Ion Cylindrical Cells under Non-Uniform Temperature Conditions
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DOI：
10.1149/2.0011709jes
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发表时间：
2017-07
影响因子：
3.9
通讯作者：
Matthew P. Klein;J. W. Park
中科院分区：
文献类型：
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作者：
Matthew P. Klein;J. W. Park
了解大型锂离子电池中电极之间以及并联电池之间发生的内部状态不均匀性是电池和电池模块设计过程的关键部分。使用LiFePO 4/C6（LFP）和LiNiMnCoO 2/C6（NMC）化学成分测试了两组独立的并联18650电池。脉冲和全容量放电进行了各种状态的充电（SOC），C-率，平均温度和温度不均匀性的水平。与NMC组相比，LFP组脉冲测试的电流不均匀性始终较低。LFP组中最热的电池产生的电流比平均值高出40%，而NMC则高达80%。相反，在电荷耗尽条件下，NMC组经历较少的电流不均匀性，并且在某些情况下，在存在不均匀温度的情况下提供几乎均匀的电流分布。结果表明，在脉冲条件下，电池阻抗的温度灵敏度越高，电流的不均匀性越大。然而，由于电荷耗尽的非均匀SOC的存在，开路电压（OCV）对SOC梯度在指示电流分布行为方面起着重要作用，其中更陡的OCV提供了使非均匀阻抗的影响最小化的校正动作。©作者（S）2017。由ECS发布。这是一篇开放获取的文章，根据知识共享署名非商业性禁止衍生4.0许可证（CC BY-NC-ND，http：//creativecommons.org/licenses/by-nc-nd/4.0/）的条款分发，该许可证允许在任何媒体上进行非商业性的重用，分发和复制，前提是原始作品没有以任何方式改变并正确引用。如需商业再利用许可，请发送电子邮件至oa@electrochem.org。[DOI：10.1149/2.0011709jes]保留所有权利。
Understanding internal state non-uniformity that occurs across the electrodes in large-format Lithium-ion batteries, and among parallel-connected cells, is a critical part of the cell and battery module design process. Two separate groups of parallel-connected 18650 cells were tested using LiFePO4/C6 (LFP), and LiNiMnCoO2/C6 (NMC) chemistries. Pulse and full-capacity discharges were performed at various States of Charge (SOC), C-rates, average temperatures, and levels of temperature non-uniformity. Current nonuniformity for the pulse testing was always lower for the LFP group compared to the NMC group. The hottest cell in the LFP group produced up to 40% more current than average, while this was up to 80% for NMC. Conversely, under charge depleting conditions the NMC group experienced less current non-uniformity, and in certain cases provided a nearly uniform current distribution in the presence of non-uniform temperature. The results indicate that higher temperature sensitivity in the impedance of a cell will cause larger current non-uniformity under pulse conditions. However, due to the presence of non-uniform SOC for charge depleting, the Open Circuit Voltage (OCV) versus SOC gradient plays a significant role in dictating the current distribution behavior, where steeper OCVs provide a corrective action that minimizes the effect of the non-uniform impedance. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0011709jes] All rights reserved.