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。在相机技术的最新发展已经允许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检测器平面强度。这一丰富的数据集的可用性使低剂量成像的材料含有广泛的原子序数的元素。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控制滞后，电压衰减和降解机制。4D-STEM低剂量成像（包括重叠关联成像）的开发、实验和数据处理方法。这项工作将涉及优化数据采集的显微镜控制和开发适当的数据处理算法。特别地，重叠关联提供了以最小的电子剂量检测轻元素并在后处理中校正任何残余光学未对准的潜力。后一种能力对于诸如锂离子电池材料的辐射敏感材料是重要的，因为不需要使用剂量来执行光学测量的微调。探讨高容量正极材料性能下降的原因。富锂阴极材料显示出更高的能量存储容量，这是由除了过渡金属之外还涉及氧化还原的O物质来解释的。这种材料表现出大的充电-放电滞后效应和电压衰减，通过O损耗解释。开发的成像能力将用于检查阴极材料在充电-放电循环的各个阶段，以了解O-损失过程是如何发生的。锂离子电池（如锂金属和高容量阴极）中的图像粘合效应。最近的工作表明，从4D-STEM数据集的重叠关联重建是敏感的电子重新分布，由于键合。这些信息对于一系列锂离子电池材料来说是非常宝贵的，其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（电子化学储能），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）研究领域的福尔斯。该项目是与慕尼黑的PNDetector公司合作，德国（pndetector.com）。学生是PN Detectors GmbH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