In situ NMR observation of the lithium extraction/insertion from LiCoO2 cathode
In situ NMR observation of the lithium extraction/insertion from LiCoO2 cathode
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DOI：
10.1016/j.electacta.2013.06.120
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发表时间：
2013-10
影响因子：
6.6
通讯作者：
K. Shimoda;M. Murakami;D. Takamatsu;H. Arai;Y. Uchimoto;Z. Ogumi
中科院分区：
文献类型：
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作者：
K. Shimoda;M. Murakami;D. Takamatsu;H. Arai;Y. Uchimoto;Z. Ogumi
可充电锂离子电池(LIBS)由于具有较高的重量和体积能量密度，目前被认为是便携式电子设备中最合适的储能资源之一。为了了解Li+离子在锂的电化学提取/插入过程中的行为，我们在塑料电池中对LiCoO2正极材料进行了7Li核磁共振测量，研究了LixCoO2(0≤x≤1)的7Li核磁共振信号的光谱演化。LixCoO2(∼0.99≤x<；1)的极窄固溶区是由LiCoO2信号在∼0ppm处的大强度衰减而明确定义的，这与顺磁性Co4+离子在极早期脱氢阶段形成的电子自旋的局域性有关。随着LiCoO2信号强度的进一步降低，出现了与导电的LixCoO2相对应的奈特移位信号ATx=0.97，然后随着LixCoO2的电化学脱锂作用，该信号的强度单调地减小到0.75。尽管本研究提供了更多的定量信息，但在情景中获得的这些观察结果充分证实了早期的研究。此外，还发现LixCoO2的核磁共振峰位随锂含量的变化而移动，其行为类似于其晶格参数的变化。在充放电循环过程中，可以清楚地观察到对电极上树枝状/苔藓状金属锂的生长和消耗。
Rechargeable lithium-ion batteries (LIBs) are currently accepted to be one of the most suitable energy storage resources in portable electronic devices because of their high gravimetric and volumetric energy density. To understand the behavior of Li+ions on electrochemical lithium extraction/insertion process, we performedin situ7Li nuclear magnetic resonance (NMR) measurements for LiCoO2cathode in a plastic cell battery, and the spectral evolutions of the7Li NMR signal of LixCoO2(0 ≤x≤ 1) were well investigated. Very narrow solid solution region of LixCoO2(∼0.99 ≤x< 1) was explicitly defined from the large intensity reduction of LiCoO2signal at ∼0 ppm, which is related to the localized nature of the electronic spin of paramagnetic Co4+ion formed at the very early delithiation stage. With further decreasing the signal intensity of LiCoO2, a Knight-shifted signal corresponding to an electrically conductive LixCoO2phase emerged atx= 0.97, which then monotonously decreased in intensity forx< 0.75 in accordance with the electrochemical lithium de-intercalation from LixCoO2. These observations acquiredin situfully confirm the earlier studies obtained inex situmeasurements, although the present study offers more quantitative information. Moreover, it was shown that the peak position of the NMR shift for LixCoO2moved as a function of lithium content, which behavior is analogous to the change in itsclattice parameter. Also, the growth and consumption of dendritic/mossy metallic lithium on the counter electrode was clearly observed during the charge/discharge cycles.