Effect of Anode Slippage on Cathode Cutoff Potential and Degradation Mechanisms in Ni-Rich Li-Ion Batteries
Effect of Anode Slippage on Cathode Cutoff Potential and Degradation Mechanisms in Ni-Rich Li-Ion Batteries
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DOI：
10.1016/j.xcrp.2020.100253
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发表时间：
2020-11-18
影响因子：
8.9
通讯作者：
De Volder, Michael F. L.
中科院分区：
文献类型：
--
作者：
Dose, Wesley M.;Xu, Chao;De Volder, Michael F. L.
基于富镍层状阴极的锂离子电池是电动汽车的最先进技术；然而，使用这些先进材料的电池的性能会迅速下降。在这项工作中，我们报告了石墨/LiNi0.8Mn0.1Co0.1O2（NMC811）全电池老化过程中的一个关键转折点，此后降解明显加速。这个转折点是通过对标准两电极数据应用差分电压分析 (DVA) 来确定的，这表明石墨的锂化程度逐渐降低，正如操作长持续时间 X 射线衍射所证实的那样，因此在充电结束时具有更高的电化学势。这种增加导致阴极电势成比例增加，并且从这一点观察到加速的阻抗增加。这种机制预计适用于绝大多数锂离子电池化学物质，特别是富镍正极，其降解对截止电压上限极其敏感，我们的工作为制定有效对策提供了基本指导。
Li-ion batteries based on Ni-rich layered cathodes are the state-of-the-art technology for electric vehicles; however, batteries using these advanced materials suffer from rapid performance fading. In this work, we report a critical turning point during the aging of graphite/LiNi0.8Mn0.1Co0.1O2 (NMC811) full cells, after which the degradation is significantly accelerated. This turning point was identified using differential voltage analysis (DVA) applied to standard two-electrode data, which shows that graphite becomes progressively less lithiated, as confirmed by operando long-duration X-ray diffraction, and therefore has a higher electrochemical potential at the end of charge. This increase leads to a proportional increase in the cathode potential, and an accelerated impedance increase is observed from this point. This mechanism is expected to be universal for the vast majority of Li-ion battery chemistries, particularly for Ni-rich cathodes, whose degradation is extremely sensitive to the upper cutoff voltage, and our work provides fundamental guidelines for developing effective countermeasures.