Multilayer Electrodes and Neutrons: A Tool to Study Lithiation Mechanisms

锂等小金属离子在合适的电极上的电化学结合和去除是可充电电化学储能的基本过程。因此，了解实际大容量电极的锂化机理对相关的基础和应用研究具有重要意义。在这个项目中，我们将使用一种新的方法来研究负极的这个问题，该方法基于多层电极和操作中中子反射仪。这种独特的组合使人们能够轻松识别基本的锂化机理，同时测量电化学锂化过程中的体积变化。这种方法的优点是，使用多层排列(同位素或化学调制)，将具有大量干涉条纹的复杂中子反射率图样转换为具有单个布拉格峰的简单图样。因此，用于描述图案的相关参数的数量将大大减少，并且可以对结果进行明确的解释。作为多层电极模型系统，73Ge/Ge(同位素)和Si/C(化学)薄膜将采用离子束溅射沉积的方法制备电极材料。在恒流循环和循环伏安法中，电极过程应该用中子反射仪进行研究。这些结果应该有助于从根本上理解改进电池所必需的基本方面

The electrochemical incorporation and removal of small metal Ions like Li into suitable electrodes is a fundamental process for rechargeable electrochemical energy storage. Consequently, an understanding of the lithiation mechanism of actual high capacity electrodes is of high interest for fundamental and application relevant research. Within this project we will investigate this problem for negative electrodes using a novel approach which is based on multilayer electrodes and in-operando neutron reflectometry. This unique combination allows an easy identification of the fundamental lithiation mechanism and simultaneously a measurement of volume modifications during electrochemical lithiation. The advantage of the approach is that the use of a multilayer arrangement (isotope or chemical modulated) transforms complex neutron reflectivity patterns with numerous interference fringes into a simpler pattern with a single Bragg peak. Hereby, the number of relevant parameters for the description of the pattern will be reduced drastically and an unambiguous interpretation of the results is possible. As multilayer electrode model systems thin films of 73Ge/Ge (isotope) and Si/C (chemical) will be investigated.The electrode material will be produced by ion-beam sputter deposition. Electrode processes should be studied in-operando during galvanostatic cycling and cyclic voltammetry by Neutron Reflectometry. The results should help to fundamentally understand the basic aspects, necessary for an improvement of batteries