Linking of Model and Commercial Active Materials for Lithium Ion Batteries by In-situ Determination of Thermodynamic and Kinetic Data

高性能锂离子电池发展的基本要求包括动力学限制和热力学稳定性的知识。这里设想的系统研究是基于一种新技术来确定温度和相变焓作为活性材料组成的函数，而锂含量是原位控制的。因此，将使用沉积在压电换能器上的薄膜，从而能够同时应用进一步的方法，如x射线衍射和阻抗谱。微重力法和稳定示踪剂以及随后的质谱法将用于研究动力学和运输路线。感兴趣的材料包括系统的传统氧化物Li(Co,Ni，M)O2 （M = Mn, Al）和新的TiO2/Si和MoS2化合物，由于阳极氧化等制备过程而显示出不同的微观结构。在确定锂离子的极限输运步骤的基础上，打算通过调整微观结构来修改活性表面或减少扩散长度。此外，将研究离子液体与上述电极材料结合作为电解质的适用性。重点应主要放在具有弱配位阴离子的体系上。这些数据，特别是电极的微观结构，将成为发展输运、缺陷化学和热力学模型的基础。同时，数据将提供给合作者进行热力学计算。

Essential requirements for the development of high-performance lithium ion batteries include the knowledge of kinetic limitations and of the thermodynamic stability. The systematic studies envisaged here are based on a new technique to determine temperature and enthalpy of phase transformations as function of composition of the active materials while the lithium content is controlled in-situ. Thereby, thin films deposited on piezoelectric transducers will be used which enables the simultaneous application of further methods such as X-ray diffraction and impedance spectroscopy. Microgravimetry and stable tracers with subsequent mass spectrometry will be applied to investigate the kinetics and the routes of the transport. Materials of interest include conventional oxides of the system Li(Co,Ni,M)O2 (M = Mn, Al) and new TiO2/Si and MoS2 compounds showing distinct microstructures due to preparation processes such as anodic oxidation. Based on the identification of the limiting transport step for lithium ions, modifications of the active surfaces or reduction of the diffusion lengths by tailoring the microstructure are intended. Further, the applicability of ionic liquids as electrolytes in combination with the above electrode materials will be investigated. The focus shall be mainly on systems with weakly coordinating anions.Those data and, in particular, the microstructure of the electrodes will form the basis to develop transport, defect chemical and thermodynamic models. Simultaneously, the data will be provided to the collaborators performing thermodynamic calculations.