Polaronic Influences on the Charge Transport Properties of Battery Anodes

电池，特别是那些基于锂离子转移的电池，在现代社会中无处不在，随着电动汽车的出现，变得更加重要。考虑到这种普遍程度，令人惊讶的是，在常见的电池阳极材料如锂钛氧化物（LTO）中发生的基本过程根本没有得到很好的理解。我们最近发现的极化子，通过周围材料的极化定位的电子，在减少LTO首次解释了氧空位的产生如何导致实验观察到的材料的电子电导率大大提高。在还原后，离子电导率也有类似的改善，这就提出了一个重要的问题，即极化子是否也起作用。因此，我们建议测试的假设，许多实验观察到的性质的LTO和镧锂钛氧化物，另一种提出的电池阳极材料，可以解释考虑极化子的发生。为此，我们将采用一种有效的固态嵌入技术，我们一起哈伯德修正的密度泛函理论，探讨不同的极化子在这两种材料中的本地化模式和它们对电子和离子电导率的影响。因此，我们将估计动力学扩散障碍，这将作为一个待开发的动力学模型的基础。这将使我们能够检查在材料的不同锂化程度（即电池的充电）、不同缺陷浓度和不同缺陷分布下任一电荷载流子的可能相关运动。总而言之，除了详细了解LTO和潜在LLTO中的传输机制外，该项目还将为改进电池阳极的合理设计标准指明方向，例如以某些缺陷模式的形式。

Batteries, especially those based on the transfer of lithium ions, are ubiquitous in modern society and, with the advent of electro-mobility, are becomming even more important. Given this degree of pervasiveness, it is quite astonishing that elementary processes occurring in common battery anode materials such as lithium titanium oxide (LTO) are not at all well understood. Our recent discovery of polarons, electrons localized through the polarisation of the surrounding material, in reduced LTO for the first time explained how the generation of oxygen vacancies leads to an, experimentally observed, much improved electronic conductivity of the material. Similar improvements upon reduction have been found for the ionic conductivity, raising the important question if also there polarons play a role. Therefore, we propose to test the hypothesis that many of the (also in operando) experimentally observed properties of LTO and lanthanum lithium titanium oxide, another proposed battery anode material, can be explained considering the occurrence of polarons. To this end, we will employ an efficient solid state embedding technique developed by us together with Hubbard-corrected density functional theory to explore different localization patterns of polarons in both materials and their influence on electronic and ionic conductivity. Thereby, we will estimate kinetic diffusion barriers which will serve as the basis of a to be developed dynamical model. This will allow us to examine the possibly correlated motion of either charge carrier at different degrees of lithiation of the material (i.e. charging of the battery), different defect concentrations, and different defect distributions. All in all, besides yielding a detailed understanding of the transport mechanisms in LTO and, potentially, LLTO, this project will also point the way towards rational design criteria for improved battery anodes, e.g. in the form certain defect patterns.