Emerging chemical heterogeneities in a commercial 18650 NCA Li-ion battery during early cycling revealed by synchrotron X-ray diffraction tomography
Emerging chemical heterogeneities in a commercial 18650 NCA Li-ion battery during early cycling revealed by synchrotron X-ray diffraction tomography
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DOI：
10.1016/j.jpowsour.2022.231589
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发表时间：
2022-08
影响因子：
9.2
通讯作者：
D. Matras;T. Ashton;H. Dong;M. Mirolo;I. Martens;J. Drnec;J. A. Darr;P. Quinn;S. Jacques;A. Beale;A. Vamvakeros
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文献类型：
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作者：
D. Matras;T. Ashton;H. Dong;M. Mirolo;I. Martens;J. Drnec;J. A. Darr;P. Quinn;S. Jacques;A. Beale;A. Vamvakeros
采用同步辐射X射线衍射计算机层析成像技术，对商用18650圆柱形LiNi0.8Co0.15Al0.5O2(NCA)电池在7次循环条件下的性能进行了研究。对空间分辨衍射图的分析揭示了与锂在正极和负极中的分布有关的多种化学不均一性。结果表明，在电池充电过程中，负极表现出不同程度的锂离子活化过程。明确地，确定了以下三个区域：均匀/均一锂化区、延迟锂化区和非活性锂化区。非活性至锂化阳极区是特定电池几何形状的结果(即，由于与这些阳极区相对缺少阴极带)，并且在整个循环实验中仍然以LiC30-30+的形式存在。在电池放电过程中，延迟的锂化区被认为对NCA的性能有直接影响，从而防止其完全锂化。此外，铝片对与其直接接触的NCA产生负面影响，导致与阴极其余部分相比不同的晶格参数a和c的演化。
Synchrotron X-ray diffraction computed tomography (XRD-CT) was employed to study a commercial 18650 cylindrical LiNi0.8Co0.15Al0.5O2(NCA) battery under operating conditions and during seven cycles. The analysis of the spatially-resolved diffraction patterns revealed multiple chemical heterogeneities related to the lithium distribution in both the cathode and the anode. It is shown that during the charging of the battery, the anode exhibits different degrees of activity regarding the lithiation process. Explicitly, the following three regions were identified: a uniform/homogenous lithiation, a delayed lithiation and an inactive-to-lithiation region. The inactive-to-lithiation anode region was a result of the specific cell geometry (i.e. due to lack of cathode tape opposite these anode areas) and throughout the cycling experiments remained present in the form of LiC30-30+. The delayed lithiation region was seen to have a direct impact on the properties of NCA in its close proximity during the battery discharging, preventing its full lithiation. Further to this, the aluminum tab negatively affected the NCA in direct contact with it, leading to different lattice parameter a and c evolution compared to the rest of the cathode.