Material strategies for high energy layered cathodes with improved stability for Li-ion batteries: investigation of doping strategies and solid-state concepts using a combined in- situ/operando approach

锂离子电池（LIB）在移动能量存储设备、电动汽车（电动和混合动力汽车）和固定能量存储等各种应用中都引起了人们的极大兴趣。为了获得未来应用所需的高能量密度，需要进一步的材料和技术开发，特别是在正极（阴极）方面。最重要的是，这种富含锂和锰的双组分“层-层”xLi2MnO3(1-x)LiMO2材料（M = Ni, Mn, Co）在高能阴极中非常有前景，在2.0 V - 4.6 V的电位范围内提供>200 mAh/g的容量。然而，目前这种类型的材料遭受电压衰减和容量损失。本提案旨在全面了解高能正极材料的降解，并以层状层状材料为重点，提出提高电极稳定性的材料和材料策略。作为工作的一部分，我们将测试和结合不同的材料策略，例如使用含锂表面层和固体电解质，掺杂高电荷阳离子，以及掺杂卤化物离子。通过对模型电极和复合电极的多方法原位/操作分析方法的联合研究，我们打算阐明晶格掺杂和涂层在结构稳定性和表面层形成中的作用。具体而言，我们建议将电子结构分析、晶体结构分析和局部有序和非均匀性分析相结合，以深入了解不可逆缺陷形成和耦合相变和退化现象。因此，特别注意电极-电解质界面的形成和电极的反应性。在其基本方向上，我们的建议也解决了其他混合导电材料或一般电极材料的关键问题，例如用于传感器或燃料电池的材料。

Li-ion batteries (LIB) have been of great interest for a variety of applications such as mobile energy storage devices, electromobility (electrical and hybrid vehicles), and stationary energy storage. To obtain high energy densities as required for future applications, further materials and technology development is required, particularly regarding positive electrodes (cathodes). Above all, the class of two-component Li and Mn-rich 'layered-layered' xLi2MnO3(1-x)LiMO2 materials (M = Ni, Mn, Co) is very promising for application in high energy cathodes, providing capacities of >200 mAh/g in the potential range of 2.0 V - 4.6 V. However, presently this type of material suffers from voltage decay and capacity loss.This proposal aims to obtain a comprehensive understanding of the degradation of high energy cathode materials with a focus on layered-layered materials, and to propose materials and materials strategies for electrodes with improved stability. As part of the work, we will test and combine different material strategies, such as use of Li-containing surface layers and solid electrolytes, doping with highly charged cations, as well as doping with halide ions. By means of a combined investigation using a multi-method in situ/operando analysis approach on model and composite electrodes, we intent to clarify the role of lattice doping and coating for structural stability and surface layer formation. Specifically, we propose to combine electronic structure analysis, analysis of crystal structure and analysis of local order and inhomogeneity to obtain insights into irreversible defect formation and coupled phase transformation and degradation phenomena. Special attention is thereby given to the electrode-electrolyte interface formation and to electrode reactivity.In its fundamental orientation, our proposal also addresses key issues for other mixed conducting materials or electrode materials in general, such as materials used in sensors or fuel cells.