Lithium-rich cathodes can store excess charge beyond the transition metal redox capacity by participation of oxygen in reversible anionic redox reactions. Although these processes are crucial for achieving high energy densities, their structural origins are not yet fully understood. Here, we explore the use of annular bright-field (ABF) imaging in scanning transmission electron microscopy (STEM) to measure oxygen distortions in charged Li1.2Ni0.2Mn0.6O2. We show that ABF STEM data can provide positional accuracies below 20 pm but this is restricted to cases where no specimen mistilt is present, and only for a range of thicknesses above 3.5 nm. The reliability of these measurements is compromised even when the experimental and post-processing designs are optimised for accuracy and precision, indicating that extreme care must be taken when attempting to quantify distortions in these materials.

中文翻译：

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使用 ABF STEM 量化富锂过渡金属氧化物阴极中的氧畸变

通过氧气参与可逆的阴离子氧化还原反应，富锂阴极可以储存超过过渡金属氧化还原容量的过量电荷。尽管这些过程对于实现高能量密度至关重要，但它们的结构起源尚不完全清楚。在这里，我们探讨了在扫描透射电子显微镜 (STEM) 中使用环形明场 (ABF) 成像来测量带电 Li1.2Ni0.2Mn0.6O2 中的氧畸变。我们表明 ABF STEM 数据可以提供低于 20 pm 的位置精度，但这仅限于不存在样品倾斜的情况，并且仅适用于 3.5 nm 以上的厚度范围。即使实验和后处理设计针对准确性和精度进行了优化，这些测量的可靠性也会受到影响，