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

该项目的目的是开发和应用基于4D-STEM的低剂量成像方法，用于成像较轻的元素和较重的元素，以使人们能够了解大容量锂离子电池的性能和退化。照相机技术的最新发展使得能够在扫描透射电子显微镜(STEM)中收集作为照明探头位置的函数的全部探测器平面强度。这一丰富的数据集的可获得性使得能够对含有广泛原子序数的元素的材料进行低剂量成像。这种能力在锂离子电池正极材料的研究中具有巨大的潜力，因为锂、氧和过渡金属之间的相互作用是控制滞后、电压衰减和退化机制的。本项目的总体目标是：i.开发包括层析成像在内的4D-STEM低剂量成像的实验和数据处理方法。这项工作将涉及优化显微镜控制的数据采集和开发适当的数据处理算法。特别是，平版印刷术提供了以最小的电子剂量检测轻元素的可能性，并在后处理中校正任何残留的光学失调。后一种能力对于锂离子电池材料等辐射敏感材料很重要，因为它不需要使用剂量来执行光学对准的微调。探讨大容量正极材料性能下降的原因。富锂正极材料表现出更高的储能能力，这是因为除了过渡金属外，O物种还参与了氧化还原。这种材料表现出很大的充放电滞后效应和电压衰减，这可以用O损耗来解释。开发的成像能力将用于在充放电循环的不同阶段检查阴极材料，以了解氧损失过程是如何发生的。锂离子电池中的图像键合效应，如锂金属和大容量阴极。最近的工作表明，从4D-STEM数据集进行的层析重建对由于成键而引起的电子重新分布很敏感。这些信息对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是否可以测量其键合的方向性来解释锂金属的机械各向异性。这个项目属于EPSRC的研究领域，包括能量(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(建立新的能力)。该项目是与德国慕尼黑的PNDetector公司(pnDetector.com)合作进行的。学生是Pn检测器有限公司的案例转换

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