Measuring Local Atomic Structure Variations through the Depth of Ultrathin (<20 nm) ALD Aluminum Oxide: Implications for Lithium-Ion Batteries
Measuring Local Atomic Structure Variations through the Depth of Ultrathin (<20 nm) ALD Aluminum Oxide: Implications for Lithium-Ion Batteries
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DOI：
10.1021/acsanm.2c02312
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发表时间：
2022-08
影响因子：
5.9
通讯作者：
Nikhila C Paranamana;Ryan C. Gettler;Henry D Koenig;S. Montgomery-Smith;Xiaoqing He;M. Young
中科院分区：
文献类型：
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作者：
Nikhila C Paranamana;Ryan C. Gettler;Henry D Koenig;S. Montgomery-Smith;Xiaoqing He;M. Young
了解纳米（<20 nm）原子层沉积（ALD）涂层的原子结构对于建立结构-性能关系和加速ALD膜在稳定电池界面方面的应用至关重要。以前的研究已经测量了原子结构的纳米ALD膜使用低温电子衍射与大（约200 nm）的光束直径。然而，对于ALD涂层，这些测量仅提供系综平均结构信息，并且不能用于直接测量通过ALD膜的深度的原子结构的差异。在这项研究中，我们使用低温扫描透射电子显微镜（STEM）本地化的电子束到一个小（约5 nm）的斑点大小，我们收集电子衍射数据在多个点沿着沉积到碳纳米管（CNT）基板上的12 nm厚的ALD AlOx膜的深度没有从基板的贡献。我们将这些衍射测量与对分布函数（PDF）分析和迭代反向蒙特卡罗分子静力学（RMC-MS）建模相结合，以比较薄膜深度不同位置处的原子结构度量。我们解释的建模结果，考虑到三维（3D）同心圆柱形样品的几何形状的CNT均匀AlOxcoating。这些测量结果证实了先前提出的ALD AlOx的两相体/界面结构模型，并表明CNT-AlOx界面处的界面层为2.5 nm厚，比先前报道的大5倍。该报告展示了直接测量纳米级材料界面上的原子结构变化，这对电化学应用具有广泛的意义，并将有助于使用ALD涂层来稳定锂离子电池界面。
Understanding the atomic structure of ultrathin (<20 nm) atomic layer deposition (ALD) coatings is critical to establish structure–property relationships and accelerate the application of ALD films to stabilize battery interfaces. Previous studies have measured the atomic structure of nanoscale ALD films using cryogenic electron diffraction with a large (∼200 nm) beam diameter. However, for ultrathin ALD coatings, these measurements provide only ensemble average structural information and cannot be used to directly measure differences in atomic structure through the depth of the ALD film. In this study, we localize the electron beam to a small (∼5 nm) spot size using cryogenic scanning transmission electron microscope (STEM), and we collect electron diffraction data at multiple points along the depth of a 12 nm thick ALD AlOxfilm deposited onto a carbon nanotube (CNT) substrate without a contribution from the substrate. We couple these diffraction measurements with pair distribution function (PDF) analysis and iterative reverse Monte Carlo-molecular statics (RMC-MS) modeling to compare atomic structure metrics at different positions in the film depth. We interpret the modeling results considering the three-dimensional (3D) concentric cylindrical sample geometry of a CNT with uniform AlOxcoating. These measurements confirm a two-phase bulk/interface structural model proposed previously for ALD AlOxand indicate that the interfacial layer at the CNT–AlOxinterface is 2.5 nm thick─5 times larger than previously reported. This report demonstrates direct measurement of atomic structural variations across nanoscale material interfaces that is of broad interest for electrochemical applications and will help inform the use of ALD coatings to stabilize lithium-ion battery interfaces.