Quantitative 4D-STEM imaging of light elements in Li-ion battery materials

该项目的目标是开发和应用基于4D-STEM的低剂量成像方法，用于对轻元素和重元素进行成像，以了解高容量锂离子电池的性能和退化情况。近年来，随着相机技术的发展，扫描透射电子显微镜（STEM）的整个探测平面强度随照射探针位置的变化而变化。这种丰富的数据集的可用性使含有原子序数范围广泛的元素的材料的低剂量成像成为可能。这种能力在锂离子电池正极材料的研究中具有很大的潜力，其中Li， O和过渡金属之间的相互作用是控制迟滞，电压衰减和降解机制。该项目的总体目标是：1。发展实验和数据处理方法的低剂量成像的4D-STEM，包括脑电图。这项工作将包括优化显微镜控制的数据采集和适当的数据处理算法的发展。特别是，平面摄影提供了以最小电子剂量检测轻元素的潜力，并在后处理中纠正任何残留的光学失调。后一种能力对于辐射敏感材料（如锂离子电池材料）很重要，因为它不需要使用剂量来进行光学对准的微调。探讨高容量正极材料性能退化的根源。富锂正极材料表现出更高的储能能力，这是由于氧化还原过程中除了过渡金属外还含有O基团。这种材料表现出较大的充放电滞后效应和电压衰减，这可以通过O损耗来解释。所开发的成像能力将用于在充放电循环的各个阶段检查阴极材料，以了解o损耗过程是如何发生的。锂离子电池中的图像键合效应，如锂金属和高容量阴极。最近的研究表明，来自4D-STEM数据集的脑电图重建对由于成键而导致的电子再分配很敏感。这些信息对于一系列锂离子电池材料来说是无价的，这里的目的是通过检查其键合的方向性是否可以测量来解释锂金属的机械各向异性。该项目属于EPSRC的能源（电子化学能量存储）、物理科学（电子光学和成像方法）和研究基础设施（建立新能力）研究领域。该项目是与德国慕尼黑的PNDetector公司（pndetector.com）合作进行的，学生与PN Detectors GmbH公司进行案例转换

The aim of the project is to develop and apply low-dose imaging methods based on 4D-STEM for imaging light elements alongside heavier ones to enable understanding of performance and degradation of high-capacity Li-ion batteries. Recent developments in camera technology has allowed the collection of the full detector plane intensity in the scanning transmission electron microscope (STEM) as a function of illuminating probe position. The availability of this rich data-set enables low-dose imaging of materials containing elements with a wide range of atomic numbers. Such a capability has great potential in the study of Li-ion battery cathode materials where the interaction between Li, O and transition metals is controls hysteresis, voltage fade and degradation mechanisms.The overall objectives of the project are:i. The development experimental and data processing approaches to low-dose imaging with 4D-STEM including ptychography. This work will involve optimising the microscope control for data acquisition and the development of appropriate data processing algorithms. In particular, ptychography offers the potential to detect light elements with minimal electron dose and to correct for any residual optical misalignments in post-processing. The latter capability is important for radiation-sensitive materials such as Li-ion battery materials because it is not necessary to use dose to perform the fine tuning of the optical alignment.ii. To explore the origins of performance degradation in high-capacity cathode materials. Lithium-rich cathode materials show higher energy storage capacities which is explained by the O species being involved in the redox in addition to the transition metals. Such materials show large charge-discharge hysteresis effects and voltage fade, explained through O loss. The imaging capabilities developed will be used to examine cathode materials at various stages of charge-discharge cycles to understand how the O-loss process occurs.iii. Image bonding effects in Li ion batteries such as Li-metal and high-capacity cathodes. Recent work has shown that ptychographic reconstructions from 4D-STEM data set are sensitive to electron redistribution due to bonding. Such information is invaluable for a range of Li ion battery materials, and the aim here will be to explain the mechanical anisotropy of Li metal by examining whether the directionality of its bonding can be measured.This project falls within the EPSRC research areas of Energy (electron chemical energy storage), Physical Sciences (electron optics and imaging methods) and Research Infrastructure (building new capabilities). The project is in collaboration with the company PNDetector in Munich, Germany (pndetector.com).Student is case conversion with company PN Detectors GmbH