Towards better estimability of electrode-specific state of health: Decoding the cell expansion
Towards better estimability of electrode-specific state of health: Decoding the cell expansion
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DOI：
10.1016/j.jpowsour.2019.03.104
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发表时间：
2019-07
影响因子：
9.2
通讯作者：
Peyman Mohtat;Suhak Lee;Jason B. Siegel;A. Stefanopoulou
中科院分区：
文献类型：
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作者：
Peyman Mohtat;Suhak Lee;Jason B. Siegel;A. Stefanopoulou
锂离子电池容易受到不利的物理和化学机制的影响，这些机制会随着时间的推移而降低其性能。出于这个原因，识别每个电极的容量和利用窗口对于电池的安全操作是重要的，不幸的是，标准容量估计方法不能提供这一点。在这项工作中，我们引入电极特定的健康状态（eSOH）相关参数，包括单个电极容量和利用窗口。我们探讨的可识别性的参数，单独使用终端电压和电压加细胞膨胀测量。这里的分析是基于受约束的克拉美-罗界（CRB）制定，它提供了参数的误差界。该模型利用电压/膨胀函数的锂化学计量的各个电极的基础上的物理相变。它示出，对应于电极中的相变的电压和膨胀的斜率变化增强了估计。因此，通过增加扩展，可以估计参数，而无需将电池放电到高放电深度（> 70%），这在汽车应用中很少发生。这使得eSOH估计对于更广泛的真实驾驶场景是可行的。
Li-ion batteries are prone to adverse physical and chemical mechanisms that can degrade their performance over time. For this reason, identifying each electrode's capacity and utilization window is important for the safe operation of the battery, unfortunately the standard capacity estimation method cannot provide this. In this work, we introduce electrode-specific State of Health (eSOH) related parameters, including individual electrode capacity and utilization window. We explore the identifiability of the parameters using terminal voltage alone and voltage plus cell expansion measurements. The analysis here is based on the constrained Cramer-Rao Bound (CRB) formulation, which provides the error bounds for the parameters. The model utilizes the voltage/expansion functions of lithium stoichiometry for the individual electrodes based on the underlying physics of phase transitions. It is shown that slope changes in voltage and expansion that correspond to phase transitions in the electrodes enhance the estimation. As a result, with the addition of the expansion, the parameters are estimable without the need to discharge the battery to a high Depth of Discharge (> 70%), which rarely happens in automotive applications. This makes eSOH estimation feasible for a wider range of real-world driving scenarios.