Practical Assessment of Anionic Redox in Li-Rich Layered Oxide Cathodes: A Mixed Blessing for High Energy Li-Ion Batteries
Practical Assessment of Anionic Redox in Li-Rich Layered Oxide Cathodes: A Mixed Blessing for High Energy Li-Ion Batteries
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DOI：
10.1149/2.0531614jes
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发表时间：
2016-01-01
影响因子：
3.9
通讯作者：
Tarascon, Jean-Marie
中科院分区：
文献类型：
--
作者：
Assat, Gaurav;Delacourt, Charles;Tarascon, Jean-Marie
富锂层状氧化物，例如Li[Li0.20Ni0.13Mn0.54Co0.13]O-2（LR-NMC），由于氧阴离子的可逆氧化还原而导致高能量密度的锂离子电池阴极，从而提高电荷存储容量。不幸的是，它们的商业化已被实际问题（即电压滞后，差的速率能力，和电压衰减），因此有必要调查这些问题是否是固有的阴离子氧化还原及其结构后果。为此，“模型”富锂层状氧化物Li2Ru0.75Sn0.25O3（LRSO）在这里被用作肥沃的试验床，用于独立地检查阳离子和阴离子氧化还原的影响，因为它们分别在低电位和高电位下被整齐地隔离。通过一个阿森纳的电化学技术，我们表明，电压滞后是由阴离子氧化还原引发的，并逐步增长与更深的氧氧化结合的界面电荷转移动力学和体扩散系数的恶化。我们同样表明，这种阴离子驱动的不良动力学随着循环进一步恶化，我们还发现，如果氧气保持氧化更长时间，电压衰减得更快。我们的研究结果实际上对LR-NMC更苛刻，传达了阴离子氧化还原风险实际问题的警告;因此，当使用这类材料追求更大的容量时，我们鼓励考虑现实世界的应用。（C）.作者（S）2016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。保留所有权利。
Li-rich layered oxides, e.g. Li[Li0.20Ni0.13Mn0.54Co0.13]O-2 (LR-NMC), lead high energy density Li-ion battery cathodes, thanks to the reversible redox of oxygen anions that boost charge storage capacity. Unfortunately, their commercialization has been stalled by practical issues (i.e. voltage hysteresis, poor rate capability, and voltage fade) and hence it is necessary to investigate whether these problems are intrinsically inherent to anionic redox and its structural consequences. To this end, the 'model' Li-rich layered oxide Li2Ru0.75Sn0.25O3 (LRSO) is here used as a fertile test-bed for scrutinizing the effects of cationic and anionic redox independently since they are neatly isolated at low and high potentials, respectively. Through an arsenal of electrochemical techniques, we demonstrate that voltage hysteresis is triggered by anionic redox and grows progressively with deeper oxidation of oxygen in conjunction with the deterioration of both interfacial charge-transfer kinetics and bulk diffusion coefficient. We equally show that this anionic-driven poor kinetics keeps deteriorating further with cycling and we also find that voltage fades faster if oxygen is kept oxidized for longer. Our findings, which are in fact harsher for LR-NMC, convey caution that anionic redox risks practical problems; hence, when chasing larger capacities with this class of materials, we encourage considering real-world applications. (C). The Author(s) 2016. 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. All rights reserved.