Fundamental Understanding on the Role of Structural Defects on Lithiation of Nanoscale Transition Metal Oxides

全球范围内正在进行广泛的研究，以寻找更好的锂离子电池材料，以增加其能量和功率。过渡金属氧化物作为锂离子电池的电极材料具有优异的性能，但由于缺乏对其电化学性能的了解，阻碍了其商业化应用的进程。特别是，需要更好地研究局部原子结构和化学成分的变化，以便为充电电池应用适当地设计它们。在材料研究部固态和材料化学计划的支持下，该项目将致力于解决这一缺点。首席研究员计划在高分辨率电子显微镜内研究电池的电化学反应，使成像能够达到原子水平。利用这种能力，可以在存在结构缺陷的情况下研究锂离子在电池电极中的运动。技术摘要纳米过渡金属氧化物(TMO)是一种很有前途的锂离子电池材料。这些材料通过转化反应进行操作，并与高能量密度相关。这些材料非常容易受到合成过程中产生的结构缺陷的影响，这些缺陷可能会改变锂离子的途径，并影响其电化学性能。这项研究的目的是了解结构缺陷(如异质界面和位错)影响TMO的锂化行为的潜在原子学机制。为了实现这一目标，纳米级的TMO在原子分辨电子显微镜中进行了实时电化学锂化处理。这一项目有望更好地理解结构缺陷附近的局域应变和电子结构的演化及其对锂离子路径的影响。此外，在存在异质界面和位错的情况下，可以研究转化反应相的结构演化。

Non Technical AbstractExtensive research worldwide is underway to find better materials for Li-ion batteries in order to increase their energy and power. Transition metal oxides offer superior performance as electrodes for lithium-ion batteries; however, the progress toward their commercial use has been hindered due to lack of understanding of their electrochemical performance. In particular, variations in local atomic structure and chemistry need to be better investigated in order to properly design them for rechargeable battery applications. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, this project will work to address this shortcoming. The principal investigator plans to study the electrochemical battery reactions inside high-resolution electron microscopes enabling imaging down to atomic level. With this capability, lithium-ion movements inside the battery electrodes can be investigated in the presence of structural defects.Technical AbstractNanoscale transition metal oxides (TMO) are promising materials for lithium-ion batteries. These materials operate through conversion reactions and are associated with high energy densities. These materials are highly vulnerable to structural defects produced during synthesis that can alter lithium ion pathways and affect their electrochemical performance. The objective of this research activity is to understand the underlying atomistic mechanisms by which structural defects such as heterointerfaces and dislocations affect the lithiation behavior of TMOs. To meet this goal, nanoscale TMOs are subjected to real time electrochemical lithiation inside atomic-resolution transmission electron microscopes. This project is expected to yield better understanding on the evolution of localized strain and electronic structure at the vicinity of structural defects and their effect on lithium-ion pathways. In addition, the structural evolution of conversion reaction phases can be investigated in the presence of heterointerfaces and dislocations.