Spatially and temorally resolved in situ Raman spectroscopy of cathode materials of Li-ion batteries

锂离子电池已被用作各种现代IT应用的移动的能量存储设备。锂离子电池在未来的电动汽车（电动汽车和混合动力汽车）中的应用以及用作固定能源方面也具有很大的意义。然而，特别是在后一种应用方面，还需要进一步的技术发展。合理开发具有更高能量密度和稳定性的锂离子电池是基于对其工作模式的基本理解。这需要开发和应用新的实验方法，以便在工作条件下对电池进行详细分析。研究表明，拉曼显微镜技术有潜力为锂离子电池的工作模式提供新的见解，特别是当它用于空间分辨分析时。该项目的目标是在电池工作条件下使用空间分辨分析，对锂离子电池LiCoO2和Li（NiMnCo）O2（NMC）阴极材料的工作模式获得新的见解。除了阴极材料的动力学研究外，重点将放在单个颗粒的研究上。考虑到碳添加剂和粘合剂材料的影响，阴极材料将作为由活性物质、碳添加剂和聚偏二氟乙烯粘合剂组成的阴极混合物进行研究。调查的主要方法将是共振增强原位拉曼显微镜，这将用于空间分辨实验（拉曼映射）和测量单个粒子。预期从共振增强的优化以及表面增强拉曼光谱（Sers）的使用和原位单元设计中的变化，该方法的灵敏度显著增加。这些研究将得到红外光谱、紫外可见光谱和X射线光电子能谱等其他方法的支持。研究的重点之一是工作条件下单个颗粒的分析。通过这种方式，我们打算探索单个粒子的荷电状态和动力学的差异。这种基础研究是非常感兴趣的关于所观察到的疲劳的LiCoO2和NMC阴极材料。设想的调查的另一个焦点是阴极材料的异质性及其动力学。在这种情况下，我们打算探索，在何种程度上的行为是由不同的阴极混合物（即碳类型的变化）的影响。作为深入了解LiCoO2和NMC阴极材料的操作模式的替代方法，将采用原子层沉积（ALD）来制备限定的Al2O3涂层。为此，通过使用原位分析，我们期望能够阐明涂层对阴极材料的行为的积极影响的起源，通过与未涂覆的材料进行比较。

Li-ion batteries have been used as mobile energy storage devices for a variety of modern IT applications. Li-ion batteries are also of great interest for future applications in electro mobility (electrical and hybrid vehicles) and for use as stationary energy sources. However, in particular regarding the latter applications, further technological developments will be necessary. A rational development of Li-ion batteries with higher energy density and stability is based on a fundamental understanding of their mode of operation. This requires the development and application of new experimental approaches allowing for a detailed analysis of the battery under working conditions. It has been shown that Raman microscopy has the potential to provide new insight into the mode of operation of Li-ion batteries, in particular, when it is used for spatially-resolved analysis.The goal of the project is to gain new insight into the mode of operation of LiCoO2 and Li(NiMnCo)O2 (NMC) cathode materials for Li-ion batteries using spatially-resolved analysis under working conditions of the battery. Emphasis will be put on studies of individual particles besides studies on the dynamics of the cathode materials. To take the influence of the carbon additive and binder material into account, cathode materials will be investigated as cathode mixes consisting of active mass, carbon additive and polyvinylidendifluoride binder. The main method of investigation will be resonance-enhanced in situ Raman microscopy, which will be employed for both spatially-resolved experiments (Raman mapping) and measurements on individual particles. A significant increase in the sensitivity of the method is expected from the optimization of the resonance enhancement as well as the use of surface-enhanced Raman spectroscopy (SERS) and changes in the in situ-cell design. These studies will be supported by other methods such as IR, UV-Vis and X-ray photoelectron spectroscopy.One focus of the investigations is the analysis of individual particles under working conditions. In this way, we intend to explore the differences in the state of charge and dynamics of the individual particles. Such fundamental studies are of great interest regarding the observed fatigue of LiCoO2 and NMC cathode materials. Another focus of the envisaged investigations is the heterogeneity of the cathode materials as well as its dynamics. In this context, we intend to explore, to which extent the behavior is influenced by different cathode mixes (i.e. variation in type of carbon). As an alternative approach to gain insight into the mode of operation of LiCoO2 and NMC cathode materials, atomic layer deposition (ALD) will be employed to prepare defined Al2O3 coatings. To this end, by using in situ analysis, we expect to be able to elucidate the origin of the positive influences of the coatings on the behavior of the cathode materials by comparison with uncoated materials.