Operando Particle-Scale Characterization of Silicon Anode Degradation during Cycling by Ultrahigh-Resolution X-ray Microscopy and Computed Tomography
Operando Particle-Scale Characterization of Silicon Anode Degradation during Cycling by Ultrahigh-Resolution X-ray Microscopy and Computed Tomography
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DOI：
10.1021/acsaem.0c02823
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发表时间：
2021-02-05
影响因子：
6.4
通讯作者：
Litster, Shawn
中科院分区：
文献类型：
--
作者：
Choi, Paul;Parimalam, Bharathy S.;Litster, Shawn
使用二维（2D）操作透射X射线照片序列和三维（3D）原位X射线计算机断层扫描的组合来表征在与商业锂离子（Li离子）电池一致的电极和纽扣电池形式中循环期间的复合硅阳极。硅（Si）颗粒的膨胀和多孔电极内的相变连续成像在循环过程中以各种速率在O（100 nm）的分辨率在一个大的O（100 μ m）区域内的利益，捕捉电极尺度效应。该成像利用了在充电期间Si的锂（Li）合金化的8keV X射线吸收系数的实质性变化。在低速率循环下，Si颗粒上的X射线信号衰减随着锂化的增加而降低。相比之下，在高速率循环下，我们观察到电极尺度处的衰减增加。这种操作成像的一个有用的特征是同时对大量非常接近的粒子进行成像。为了捕捉这样一个大量的Si在循环过程中的转换，我们引入了标准偏差分析的操作性透射X射线照片序列。在循环中的关键时刻，将来自X光片的相同感兴趣区域重建为3D体积。Si颗粒断裂，电极膨胀，和粒子脱离集流体中观察到的所有重建的体积。这项研究证明了结合2D operando和3D原位X射线成像技术在商业相关电极格式中在亚微米颗粒尺度上研究电池材料动态行为的独特能力。
A combination of two-dimensional (2D) operando transmission X-ray radiograph sequences and three-dimensional (3D) in situ X-ray computed tomography was used to characterize a composite silicon anode during cycling in an electrode and coin cell format consistent with commercial lithium-ion (Li-ion) batteries. Silicon (Si) particle expansion and phase transformation within the porous electrode were imaged continuously during cycling at various rates at O(100 nm) resolution within a large O(100 mu m) region of interest that capture electrode-scale effects. The imaging utilizes the substantial change in the 8 keV X-ray absorption coefficient with lithium (Li) alloying of Si during charging. At low rate cycling, the X-ray signal attenuation over the Si particles decreased with increased lithiation. In contrast, at high rate cycling, we observe increased attenuation at the electrode scale. A useful feature of this operando imaging is the simultaneous imaging of a large number of particles in close proximity. To capture the transformations of such a large number of Si during cycling, we introduce a standard deviation analysis of the operando transmission X-ray radiograph sequences. At key instances in the cycling, the same region of interest from the radiographs was reconstructed into 3D volumes. Si particle fracture, electrode expansion, and particle detachment from the current collector were all observed in the reconstructed volumes. This study demonstrates the unique capability of the combined 2D operando and 3D in situ X-ray imaging techniques in investigating the dynamic behavior of battery materials at the sub-micrometer particle scale in commercially relevant electrode formats.